if you didn't know, handcent lets you customize the vibrate patterns for your text messages or even for different people in particular.
Settings --> Notification Settings --> Vibrate Pattern --> Custom
post your favorite ones!
0, 250, 200, 250, 150, 150, 75, 150, 75, 150
(the numbers mean milliseconds the vibrate is off then on then off then on; for my pattern it would be 0 off, 250 on, 200 off.. etc.) you just have to experiment with it and you can make some pretty unique vibrate patterns. its really helpful for determining whose texting you without taking it out of your pocket!