Uh, I'm not a nickname expert or anything but I like names and giving nicknames to people, so I tried this out. Sorry that most of these are kinda cheesy. :S
1. Tommy
2. Tom-Tom
3. aTOMic
4. Tomithy
5. Ton
Tom Yasumi goes by Tom.
Tom Ljungman goes by Tom.
Tom Kindle went by Tommy, and Tom-Tom.
Tom Petska goes by DJ Tom.
Tom Mikota goes by Tom Bombadil.
Tom Wang goes by Super Tom.
Tom Seaver goes by Tom Terrific, and The Franchise.
Tom Zaleski goes by Tom Z., and TZ.
Tom Cruz goes by Tom Cruz, and Tommy.
Tom Sizemore goes by Tommy.
Tom Seim goes by Zero.
Tom Twyman goes by TT.