I've been using Fire as my IM client on OS X but after reading an article on /. I tried Adium, it's brilliant and what do you know tabs feature, which is always a massive bonus. If you're still using individual IM clients (ie one for MSN and one for ICQ) then you need to try out Adium or on Linux Kopete (all of which are free).
In the same article it mentioned microsoft remote desktop connection, so I gave it a try and it rules, I can now control my networked XP box from on my Mac. It's free too.
I've been on ebay alot lately trying to get stuff for my office, printer and stuff, and I kept getting outbid in the last seconds. I read up about this and there is something called "sniping" where an application or "listener" can place a bid in the dying seconds of an auction. I couldn't really find a good one that didn't involve giving people money of my ebay password so if you know of a good sniping tool let me know.
Dave Winer today mentioned the new Safari browser that is to appear in the new version of OS X(Tiger). The new version of Safari has built in RSS support and it looks absolutely amazing. Still no update on Aggreg8 yet but looking at this nobody (using a mac anyway) is ever going to want a third party RSS reader ever.