A nice little flash program that lets you design a variety of guitars, from a couple of Gibson and Fender classics to Ibanae that could blind you:
http://www.yajimastringworks.com/tct/yswtct-kisekae-e.asp
I was able to make a mock-up of my LP with Bigsby:
See how the off-white LP Standard would look:
An intriguing SG:
Mmmm... Telelicious:
On the practical side, a good way for n00bs to learn about all the various options, and what people mean by "spalted maple" etc..
Try it. I found it a somewhat superior experience to working.