Posting here, sorry i didn't see this thread but have limited time and have had for some time, else i would contribute more.
Also updating the numbers now that i have installed some of the last programs, but still less then before since i did not use some of them anyway....

Normal N900 that is now taking a rest:
Running Power50
RAM: 147MB
SWAP: 107MB
Total: 254MB

Other N900 that is now primary:
Running cssu3 Thumb 14
RAM: 124MB
SWAP: 81MB
Total: 205MB

But all in all i have only install the basics and contacts, g.talk and skype running.
So memory usage is subject to change, will properly post again in a month or something