Hey guys, I've mentioned the motion sensor alarms before, but someone made a good point about the cheap plastic case they reside in(especially the handlebar mounted ones) - So they(the dirtbag thief) could just smash it to shut it up. BUT! They make locks(cable/chain/etc) with alarms built into them. ie.-inside the STEEL case. I don't think I can post links yet, so just Google "alarmed bicycle lock" to check them out. Some are as low as $20, but higher security is better piece of mind, right?
atm, I'm still using a chinese frame
mount motion sensor($10), but it's tucked in behind my chain guard really low, so it can't be smashed easily(I hope). On the highest sensitivity the damn wind will set it off, lol, and if I bump the bike while punching in the code it'll go off 'loud as he(ll)', with every passer-by watching me like a hawk... it definately gets people's attention!
Oh, and of course, always park in a high traffic area. It's easier for some punk to steal your ride from an inconspicuous spot, compared to next to the front door of WalMart.