Looking forward to seeing this info. I'm technically challenged and would love to have the resorts on my signature too. So let's here it from you techies out there!
It took me a while to figure it out. I think the easiest way is to find apicture from somebody else who has the resort you want. Put your mouse over the picture and then click the right mouse button. Look at the properties, and copy the name of the file (CTL-C will copy the name once you high lite it)
Next go to your user CP and edit your signature. Add a IMG command that looks like this: