Email: mail@johnoxton.co.uk | Tel: +44 (0)20 8133 0443
Some OS X apps I have been using for a little while without problems:
Open up any other computer right on your desktop, very handy and works an absolute dream between two Macs.
http://sourceforge.net/projects/cotvnc/
Need a screen shot without all your desktop clutter and sensitive client files in shot? Desktop curtain hides it all without you having to lift a finger.
http://www.versiontracker.com/dyn/moreinfo/macosx/26396
Probably the coolest feature, apart from showing you how healthy your battery is, is that it tells you how old your Mac is, handy if you are planning on buying second hand.
http://www.coconut-flavour.com/coconutbattery/
One keyboard, one mouse, several Macs. If you've tried and failed to get Synergy configured, give Teleport a whirl instead.
http://www.versiontracker.com/dyn/moreinfo/macosx/22339
Windows Media® Components for QuickTime. I am finding them a little buggy but they do work.
http://www.flip4mac.com/wmv.htm
Finally Google Earth on a Mac, very addictive, very cool.
Very nice open source feed reader with search and smart folders.
http://www.opencommunity.co.uk/vienna2.html
There are more advanced BitTorrent clients out there but Tomato Torrent feels like it belongs on a Mac and it is very simple to use.
I wouldn't be without AppleJack and it's just had an upgrade.
http://applejack.sourceforge.net/