The standard size signature is limited to 100 x 500. TGF Sponsors are allowed 150 x 600. There are a couple of different ways to do multiple pics. You can use photo editing software to merge several pics into one and then resize the whole thing down, or you can resize them individually and insert them separately in your signature. That's what I did with mine.
You're welcome! There are some folks on the board who know how to make really nice signatures, via the software method. Perhaps they'll chime in as well. I've tried it a little bit, but didn't seem to have the patience for it.