As Weatherman already said, PalmGear used to be a great resource but they've recently quit offering freeware - and unfortunately that means that if you Google for a particular freeware app a lot of the links are also dead Some alternatives are Handango, MyTreo.net, PalmInfoCenter.com, and I recommend Freeware-Palm.com instead (a lot less annoying than freewarepalm.com IMHO).

If you have something in particular that you're looking for let me know... I've got quite a large collection of Palm apps. I haven't been able to officially try them out on my N810 yet because I'm not allowed to touch it until Xmas. I'd be happy to share what I've got or at least might be able to point you in the right direction.