A "GUID" Question

I need to create a bunch of GUID's for a program I am working with. Problem is I want to create a shorter version of the 40 character length GUID .Net has to offer. I don't need the GUID to be worldwide unique, just application unique. The reason is each GUID is sent continously to clients over the net and I need a Unique ID for each differnt object in my application but I want to optimize the bandwidth as much as possible. Sending out 40 character length object ID's in large volume isn't going to cut it..

Anyways does anyone know of another good tip or trick to generating a short length (Application)UID?