Next time you've got some face time with—let's call him Jarvis, be sure to snap a picture with your device. Now that his smiling (or laughing, or groaning or whatever) face is in your My Pictures folder, here's all you have to do:

From your home screen, choose Menu, My Stuff. Select My Pictures and when the thumbnail images come up, scroll over to the best (or worst, it's up to you) one of Jarvis. Click Menu, Set As.

Then, from your contact list, scroll down to Jarvis (he's in there, right?). Press Select. Next time he calls, viola! It's his photo not (just) his number that pops up.