I was looking for some software to sync my Google Calendar to my N73 phone. I'm going to try out GCalSync and let you know how it goes.

I thought I'd ask the collective what, if any, third party apps they have on their phone.

I use:
Autolock
Gmail
Google Maps

I occasionally use:
Opera mini (In case a site is too big for main browser)
S60SpotOn (use the camera flash as a torch)

I rarely use:
mIRGGI (IRC client)
PuTTY