aluminum ones are easy to break if you don't know what you're doing. don't put more than a few pound inches of torque on one at a time and use a lug nut star pattern to evenly distribute the load.
even then, aluminum isn't necessarily worth the weight it will save for crank bolts. that's one place where steel weight is worth the strength.
i bought tubes.
i had to, because lying in bed half asleep last night i was awoken by a loud "BANG!" from my bike, which happened to be five feet from my bed. crazy, because it wasn't a slow leak and i had ridden on the wheel for two days just fine. then sitting around, it blows with a millimeter long V shaped tear right where the rim tape is on the very bottom of the tube next to the stem. patch fails, nothing stuck to the tape or inside the wheel... just up and exploded.
if i was a baller, i'd buy some avid shorty ultimates and a mw vandal. my bags and breaks are driving me crazy.
oh, and i bought a skink copy light from deal extreme and some rechargable aaa's. they'll get here in a week or two.