Brett has created some really useful tools around markdown amongst other things. Check out his website.

This is a brilliant Mac terminal that emulates the old green-screen devices. Huge amount of customisation. Warning: long periods of use will give you a headache! :)

Simple way to build and install open-source software on Mac systems. Although Mac OS is based on BSD Unix, there are some subtle differences, which make building and running open-source tricky.

Allows quick addition of additional tracks, such as subtitles, to existing MP4 movies.

Virtual Machine for Mac. This is a competitor to Parallels, which I actually prefer. It's a close race though. VMWare are the masters of virtual machine technology on Windows.

Virtual Machine that is closely integrated with the Mac. Parallels only create VM software for the Mac (not Windows). I find it better and faster than VMWare Fusion, but it's a close race.

Complete home finance package. Allows you to easily track your bank and savings accounts, credit cards, etc. Monitors how well you are staying within budget (its primary purpose, hence the name). Probably the best accounts package for the Mac.

The essential tool for creating a bootable copy of your Mac's primary disk in case disaster strikes. Time Machine is ok, but it will take you ages to restore your machine. With SuperDuper, you will be up and running immediately - simply boot the clone.

Screen casting tool for the Mac. Allows capture of HD desktop, audio and video via iSight or an external video camera. Download a fully functional trial.

Presentation tool to make your mouse pointer stand out. Can also display key presses on the screen. Also useful for Screen Casting.

Professional Project Management tool for Mac. Easy to use and full featured. Don't ever use Microsoft Project again!!

This website allows you to look up alternatives to software that you use or have heard of. Can be very useful when you know the kind of thing you want, but the solution you found is no good.

Streaming music service. There is a free version, but by paying £10 a month, you get radio stations (continuous music channels) and no adverts interrupting your listening. They have most things you could think of.

Evernote is a cross platform service that allows a central store of notes. Can store photos, web pages, links, or general notes.

DropBox is a service that allows you to synchronise a folder (with subfolders) on one computer with other computers via a cloud storage mechanism. 2GB of storage is free, but you can pay a monthly fee for 50-100GB. Works on Mac, Windows and iOS.

Having different passwords for each website you visit is very important. How do you manage to remember then all though? This is where 1Password comes in. It allows you to store your miriad of passwords using just one. It is possible to sync your encrypted password file via DropBox which makes your password available on Windows and iOS also.

Don McAllister is based near Liverpool and produces world renouned weekly tutorials for the Mac. Over the years he has produced videos for most of the good applications out there.

This company produces application for the Mac and, more recently, for iOS devices. I have licenses for most of their products including OmniGraffle (a powerful diagramming package), OmniOutliner (an flexible outlining tool) and OmniFocus (a GTD task management tool).

This is an essential plugin for Finder on the Mac that, amongst other things, give a tabbed view of your file system (multiple windows). It also does nice things like put all your folders at the top. There is also a HUD view, that causes finder to slide up from the bottom of the screen.

Skitch is a powerful screen capture tool for Mac OS X (they are working on a Windows version I believe). It has a fantastic interface and is essential if you create tutorial documentation. It allows you to resize, crop, and annotate captures, taken in wide variety of ways, such as screen, window, iSight, crosshairs, etc.