I’ll second Soon I Will Be Invincible and the works of Bill Bryson. Excellent books and exactly the sort of thing you’re looking for.
I’ll add The Flashman Papers (any of them), anything by Jeremy Clarkson (try The World According To Clarkson to get you started), The Red Dwarf books (Infinity Welcomes Careful Drivers, Better Than Life, Backwards, and Last Human), and finally H. Beam Piper’s The Complete Paratime.
Banvard’s Folly: Thirteen Tales of People Who Didn’t Change the World by Paul Collins
Conquistador or The Peshawar Lancers by S. M. Stirling
Freakonomics: A Rogue Economist Explores the Hidden Side of Everything by Steven Levitt and Stephen Dubner
The Harvest by Robert Charles Wilson
Kahawa by Donald Westlake
Poplorica: A Popular History of the Fads, Mavericks, Inventions, and Lore that Shaped Modern America by Martin Smith and Patrick Kiger
The Princess Bride by William Goldman
Prisoner’s Dilemma by William Poundstone
The Pyrates by George MacDonald Fraser
Resurrection Day by Brendan DuBois
Scams, Scandals, and Skulduggery; Cheats, Charlatans, and Chicanery; and Fakes, Frauds, and Flimflammery all by Andreas Schroeder
Thank You for Smoking by Christopher Buckley
World War Z: An Oral History of the Zombie War by Max Brooks
Any of C.S. Forester’s Horatio Hornblower novels
Any of Rex Stout’s Nero Wolfe mysteries
Robert Heinlein’s Juvenile novels
any Frederrick Forsyth thriller, especially the earlier ones like Day of the Jackal
As fond as I am of Mr. Forsyth’s work, I don’t think any of it qualifies as “light” or even “fun”. They’re ripping yarns and great stories, but possibly not what the OP is looking for IMHO.
Fun? Light? Quick? -
Hitchiker’s Guide (Most anything by Douglas Adams)
For stupid PUNishment, Piers Anthony, anything in the Xanth series.
Also by Piers, enjoyable, but different, the Incarnations of Immortality series.
Light can mean any book which is readily accessible and not intellectually deep - a Stephen King novel, for example, can be considered light reading even if its subject if horror.
Our definitions diverge. I find Forsyths’s work easy to pick up and read and get involved in.
Personally I wouldn’t call Stephen King “light” reading either, so it’s probably best to just agree to disagree on the subject, I think.
I came into recommend this, too, so I guess I will third it. Fun.
I recommend Top 10by Alan Moore, Gene Ha, and Xander Cannon (who used to be a regular Doper). It’s basically Hill St. Blues set in a world where pretty much everyone has a super-power of some sort. Moore was a huge fan of HSB - where everyday drudgery of work was punctuated by character’s personal dramas, relationships and explosive moments of police action. It’s not always light - but it is very easy to read and extremely satisfying. I would easily rank it with Watchmen, V, Miracle/Marvelman, etc., for what it is trying to do…
How about my namesake Icerigger by Alan Dean Foster, a very light SF adventure story.
Tanya Huff’s Keeper’s Chronicles series. Summon the Keeper is first. Very funny.
Jitterbug Perfume by Tom Robbins. Just a real fun read.
Bob Harris’ “Prisoner of Trebekistan” might fit what you’re looking for. Autobiographical story of, as stated on the cover, “one of Jeopardy!'s biggest winners… and losers.” You don’t have to be a Jeopardy! fan to enjoy it, although it helps. Lots of personal stuff mixed in with the game show stuff. You’ll laugh! You’ll cry! You’ll :eek:!
ETA: Forgot to mention that I tore through this book in a weekend, which is very unusual for me.
I also really liked his book Who Hates Whom: Well-Armed Fanatics, Intractable Conflicts, and Various Things Blowing Up, A Woefully Incomplete Guide, but I don’t know if I’d call it light. 
How about Dave Barry’s Big Trouble
Anything by Lewis Grizzard, a Great American, except My Daddy Was a Pistol and I’m a Son of a Gun.
Comics!
Lamb: The Gospel According to Biff, Christ’s Childhood Pal, by Christopher Moore.
Anything by Christopher Moore
There I fixed that for you.
The Grasshopper Trap by Patrick McManus. Just silly fun!