I think we've had one of these posts a long time ago, although I didn't find it when I searched for it. Since I've made the upgrade to snow leopard and got a new macbook pro, I thought I'd post the apps I really like.
P.S. Sorry for not posting links, but you can find almost all this on versiontracker.com
[b]Gimp[/b] - Yay opensource image editing!
[b]Jumpcut[/b] - Copy/paste history in an easy to use statusbar dropdown. I love this program :)
[b]Flip4mac[/b] - Ability to pay windows movie files
[b]xpad[/b] - Really awesome notepad program. Best one i've found. Easy to use, auto save, just brilliant.
[b]istat menu[/b] - I love seeing my CPU/memory/disk history in the status bar :) I also like the way they do date/time better than the mac way cause you can put a fun little ical like icon up there to show you the date as well
[b]Filezilla[/b] - The interface isn't super intuitive, but this is a great FTP client.
[b]Adium[/b] - Everyone knows how awesome this program is for AIM, but did you know that it will also allow you to add facebook chat, and gmail chat as well???
[b]Addressbooksync[/b] - Lets you sync names, pictures, and birthdays from your facebook account to your address book. Won't transfer anything else due to a violation in facebook's TOS
[b]Quinn[/b] - best tetris version in history :) I'm a sucker for the cool sound effects and the undo button :)
[b]iwork 09[/b] - Really solid. I wasn't much of a fan of previous versions, but this one I can live with. Although I do wish pages could do border art.
[b]Notebook 10[/b] - I use the smartboard a lot, but I also like the software for making quick presentations.