really depends what your doing with it..
on my TM600 i always install
cccam info "does what it says on the tin"
Tuxbox Commander "usefull for manually editing configs from TM remote"
WeekEPG "for epg data.."
Samba "this probably isn't very usefull for you, it's a network file sharing plugin i use it to share recordings on my tm600 usb drives to windows PC's on my network"