I've just been wondering the same thing.
All my processes seem to be using even more memory than yours
it's even weirder because...
-I don't even have any sites really running on it either
-I'm running 32bit
-also the mem usage seems to creep up quite quickly and i was having to restart the chunky services quite often
I saw a perl script somewhere that'd optimize mysqld, but i cant seem to find it again.. not sure if that'll help..
tried editing the clamav config file, but i didnt manage to lower it