Some of it depends on the dog... Here are a few possibilities...

Herc (If the parents were big, nothing worse than naming a 50lb sized dog Herc)

Buddy (if its friendly)

Digger (for obvious reasons)

Tug or Tugger (regarding to size)

Or run with the chocolate theme...

Reese (because your chocolate lab will be filled with peanut butter sooner or later,have you seen a lab around a garbage can?)

Dark (as in dark chocolate, depends on coat color)

Chunk

Chip (mentioned previously I know)

Jersey (go from Jersey cow to milk to milk chocolate)

If you know the registered name of the parents it might give you/us more to work with. That way you can relate the offspring back to the line, etc.

Ok Dark stinks, I admit it, but it came to mind so I wrote it down.