The AVRs look pretty cool.  A Basic Stamp will do it for
you.  But for quick and easy, you can get a number of things
including this:
   http://www.weedtech.com/ 

look at the digital IO module.  16 ins or outs.  Based on a PIC.
Take ascii commands via serial, will send state change info to you,
to latched outs or pulsed, etc.  And you can chain them together.
$70 plus some housing and a little power and you're done.