definitely install the radio 2.15.
all you do it drop the radio img on your sd card and install it from recovery mode. i get maximum signal now where as i was only getting 1 bar on radio 1.00.
i'm a big fan of the
sense-less rom's adrynaline has put out (check the rom sub-forum). use one of the deodexed versions as well, it will give you the most options for customization down the road.
also, get the
latest version of wireless tether that supports ap mode. you can now run screenshot apps, vnc server, busybox... and you can delete any of the bloatware that exists on your device that drives you nuts.
other peeps are into custom boot screens or hacked out notification bars. look around on here and xda forums and you'll find plenty things to do.