ActiveX control for using input output / relay cards
http://www.industrialmightandlogic.com
I like it; its easy to use.
(cut'npaste from website - sorry about the formatting)
Supported Interface Boards (I/O cards):
USB: K8055 Velleman Electronics
VM110 Velleman Electronics
k8061 Velleman Electronics
Parallel: K2805 by Dick Smith Electronics (not available any more), see Silicon Chip for more information
Generic Parallel Port Digital I/O Board Various example boards can be found at:
QualityKits - QK74
Kitrus.com - Kit 74
Electronickits.com - ck1601
Audon Electronics - PPO-RL8
Jacar Electronics - KV3590
Jim Fuller's Resource Site - Simplified IO Interface