Light reads perfect for the beach, the laundromat, the repair shop or the long plane ride. Any of these would make an excellent study break and are a good way to acquaint yourself or a friend with the genre. Try these authors:
Douglas Adams (He also wrote for Monty Python's Flying Circus)
Piers Anthony (For lovers of wordplay. He does like a pun, and he works hard for them.)
Robert Asprin (Also look under T for the "Thieves' World" series)
Arthur C. Clarke (accessible Hard Science Sci-Fi)
Neil Gaiman (also in Kids Fantasy section)
Harry Harrison'sStainless Steel Rat series (A lot of Flash Gordon plus a little Denis Leary. Safe for teen readers, though)
Keith Laumer (Fun and games in the Interstellar Diplomatic Corps)
Terry Pratchett (Spoofs everything from Sword-and-Socerer books to the Apocalypse)
Spider Robinson (Bawdy and hilarious. Not so much science. Paranormal fans would like him)
Don Sakers (Silly fun)
Christopher Stasheff (Not for public transportation if you're the kind that laughs out loud at books)