Q (£free) : Parallels is great for installing virtual machines (in a nutshell you can run Windows Vista in a window within OS X) but at $80, it doesn’t come cheap. Q is free and almost as good.
Afloat (£free) : Afloat adds options to alter the transparency or make windows float on top to the Window menu of all Cocoa based applications (Quicktime, Colloquy, Adium, Safari etc). A must!
Azureus (£free) : The best bittorrent client for features with lots of plugins. It’s way ugly though.
Toast 7 (£60 from Amazon) : Excellent burning software! Very feature rich and also extremely easy to use with support for burning divx DVDs.
SimplyBurns (£free) : Don’t want to shell out for Toast but want a decent burning app? Use this.
Transmit ($30) : The best ftp client around. I don’t use ftp very often but when I need to I’m glad I have Transmit at hand.
Cyberduck (£free) : But if you don’t want to pay for Transmit then Cyberduck is pretty adequate.
FFview (£free) : My personal choice for viewing comics and manga.
FileCutter (£free) : Adds something to OS X that Apple should have done years ago: cut via a context menu within Finder!
SuperDuper (£free/$28) : Excellent software for backing up your data to an external HDD and making it bootable (it takes me under 5 minutes to backup 65GB of data via the ‘smart update’ feature). It’s free to do exact clones of your HDD but you will need to register it to get scripting and scheduling functionality.
Wallet ($15) : Keychain is very good for storing passwords (it comes with OS X) but Wallet can give you more versatility if you need it.
Pixen (£free) : A good pixel editor and animated gif creator.
UNO (£free) : Don’t like “brushed metal” and would prefer a more unified look to OS X? Install this.
BetterZip ($20) : It’s like Winrar for OS X. Very useful for opening, extracting and creating rar, zip, 7zip etc files.
Acqlite (£free) : A very good gnutella client for all your porn and mp3 needs.
Adium (£free) : Connect to MSN, AIM, Yahoo and Jabber via one application. The default dock icon is a bit obnoxious so I recommend using the Milk dock icon set instead.
aMSN (£free) : Adium is my personal favourite but if you need to use your webcam try aMSN.
Games console emulators (£free/nagware $25) : Richard Bannister’s emulators are fantastic!
Growl (£free) : A notifications application. Very useful for telling you when a download or torrent has finished downloading or that somebody has messaged you on irc.
Nufile (£free) : Do you wish that you could right click in Finder and select to create a new file like you can in windows? Now you can.
NeoOffice (£free) : Basically a native port of OpenOffice 2 but much better (OO is horrible in OS X). If you don’t want to shell out £100+ for MS Office then this is a very good alternative.
Unison ($25) : A usenet application from the guys who brought you Transmit. It is very easy to use and makes the whole usenet thing much less intimidating.
VisualHub ($23.32) : A very easy way to convert video files into whichever format you like such as DVD, iPod, flash, VCD and PSP.
Delicious Library ($40) : This is a neat little app. Essentially cataloguing software, you put the barcode up to the iSight webcam and it adds it into your virtual bookshelf along with artwork and information from amazon. You can use it for books, DVDs, music and games.
TinkerTool (£free) : OS X has a lot of hidden settings (which are fairly innocent) that it won’t let you touch. This little application allows you to mess with them (don’t worry you can’t screw up your Mac with this).
VLC (£free) : This will play any video file you throw at it. Quicktime is much more pleasant to use but VLC has better compatibility.
Realplayer (£free) : Very useful for the BBC news website. Don’t worry, it’s not nearly as obnoxious or obtrusive as it is in windows (it doesn’t ask for your personal details nor does it take over your file permissions).
Skype (£free) : The OS X client for Skype. There’s also a beta of version 2.0 which should be stable.
SeaShore (£free) : If like me you can’t afford Photoshop and don’t need advanced image editing features anyway then try out SeaShore. It’s still in alpha status but it has been reliable for me so far.
Graphic Converter ($30) : Another image editor. It’s pretty good but you may as well pay the extra £20 for Photoshop Elements if you’re going to pay for this sort of application.
Xee (£free) : An image viewer. Very useful for navigating a series of images.
Chicken of the VNC (£free) : A nice little VNC client with a silly name.
Colloquy (£free) : A very good IRC client, especially in “bland” mode.
Saft ($12) : A plug-in for Safari that adds lots of extra features (see their website for a list). Crash protection and being able to load and save browser windows (and thus your open tabs) are very useful.
Camino (£free) : I don’t recommend Firefox (it’s excellent in XP but it feels a bit alien in OS X due to ugly windows style radios and buttons) but if you don’t like Safari (why?) try out Camino instead. Like Firefox it is based on Mozilla.
Quicksilver (£free) : I use this to launch applications that aren’t in my dock but it’s a lot more versatile than that.
Visor (£free) : Makes the terminal accessible via a Quake style console when you press a hot-key.
MenuMeters (£free) : This displays RAM, CPU and network activity in the menu bar.
OS X looks after itself really so you don’t need to defrag your HDD. If you’re in the mood for tinkering then Onyx (£free) or Cocktail ($15) can be used to clear caches and what not.
OS X comes with a lot of stuff you might not need including lots of iLife components, language files and printer drivers. To help you trim the bloat, use Disk Inventory X (£free) and Monolingual (£free).
VLC (make sure you download the correct version for your processor!) will play just about any video file you throw at it out of the box but if you prefer Quicktime then install these codecs. Doing so will enable these files to be played in iTunes, Quicktime and Frontrow so it’s worth doing.
Perian enables support for a ton of codecs in one fell swoop, Flip4Mac enables WMV support and A52 enables AC3. For your Flac and OGG needs install the Xiph Quicktime component. Matroska QT will enable MKV but it’s still very early in development (no subtitle support and it’s a bit slow).
With the above installed you will able to play just about anything. The exceptions are x264 and SRT (subtitle) files whilst MKV support is still a bit alpha-ish. You can fall back on VLC for these files.
Oh yeah, want to use Quicktime but don’t feel like shelling out for Quicktime Pro just for the full-screen functionality? QT Full Screen is your friend.
Mail is a very good program for your basic email needs but you can also customise to make it even more versatile. Here is a long list of them and here is a top 10 of the best.
Sing That iTune! : Pulls album art and lyrics off the net and saves the information into your music files.
Tubetrack : Displays arrivals and departures information for any train or underground station. Perfect for checking times at a quick glance just before you leave the house.
BBC Weather : A nice weather widget that gets information from the BBC Met Office.
BBC News : A news ticker.
Sky Sports Football News : A news ticker for football.
iCal Events : Shows your iCal events for the next one to fourteen days.
UK TV Guide : It does exactly what it says on the tin.
Mac Related Websites
MacCentral : Mac news
Mac Rumours : Mac rumours
MacInTouch : Mac information
The Unofficial Apple Weblog : Blog
MacNN : Mac News
Version Tracker : Mac downloads
MacUpdate : Mac downloads
macosxhints : OS X hints and tutorials
MacSlash : The Mac section of slashdot
Daring Fireball : Blog
Macintosh Garden : Mac abandonware
Macintalk : Mac articles