Gerald Durrell has written stack loads of novels, mostly about his adventures wandering the world collecting and studying animals for his zoo, and also about the zoo itself. They tend to written in the same humourous style as ‘my family…’
Oh, and to answer the OP, try Robert Rankin, especially the Brentford Trilogy:
The Antipope
The Sprouts of Wrath
East of Ealing
The Brentford Chainstore Massacre
The Brentford Triangle
(not in that order)
and I’ll fifth (i think - I lost count) Terry Pratchett, too
1.) I’ll second Bored of the Rings It’s hilarious if you’ve read the trilogy.
2.) Tom Weller’s two books Science Made Stupid and Cvltvre Made Stupid are tragically out of print. Brilliant sendups of those “How and Why”-type science books.
3.) I know this is an either/or thing, but I’m in the 50% or so of SDMB readers who love Dave Barry. Get his Book of Bad Songs as a good intro. I gave my sister (a non-Barry person) a copy for her birthday and she laughede her head off. I love almost all of his books (well, after the first half-dozen or so. I find “The Taming of the Screw” and his other illustrated books boring. Anything from Bad Habits on is good.)
4.) It’s out of print, but A. Whitney Brown’s book is excellent.
5.) Ditto Alan King’s out-of-print books Help! I’m a Prisoner in a Chinese Bakery and Anybody who owns his own Home Deserves it.
6.) Mike Nelson’s Movie Megacheese – superb lunacy from the head writer (and later chief experuiment of) Mystery Science Theater 3000. His description of the gun battle in the Clint Eastwood-directed The Bridges of Madison County had me on the floor.
I concur that the Hitchhiker’s Guide series is funny, and would also recommend it.
But the only books that literally (and I mean literally) make me laugh out loud (which is annoying to my wife when she’s trying to sleep, but she does it to me too) is the series of books by Janet Evanovich, featuring the antics of bounty-hunter Stephanie Plum and her weird collection of family and friends…
One For The Money
Two For The Dough
Three To Get Deadly
Four To Score
High Five
Hot Six
Seven Up
Hard Eight
Patrick McManus is really funny, laugh-out-loud humor. His story on “tenner shoes” had me and a roommate literally rolling on the floor laughing.
If you like Ireland, or (minor) travel books, check out McCarthy’s Bar by Pete McCarthy. It is very funny.
Health warning…Do not read on trains for fear of snorting on a stranger.
Any of Robert Asprin’s Myth books. Very good. 
Phil Foglio’s Illegal Aliens. LOL 
I will second LolaCocaCola’s suggestion of Naked (David Sedaris)
I would recomend ANYTHING by David Sedaris. These books are the kind that have you snorting with laughter about every six pages.
I opened this thread specifically to recommend David Sedaris. I was reading “Me Talk Pretty One Day” on an airplane, and had tears of laughter streaming down my face. It got to the point where I had to lay the book in my lap to compose myself. I would then pick up the book, glance at the next word, convulse with laughter, and have to put the book down again. The woman across the aisle was eyeing me the whole time, and she finally couldn’t stand it, and had to ask me what I was reading. Damn that man is funny.
“High Fidelity” by Nick Hornby was another laugh out loud book for me. And “A White Merc With Fins” by another British author I can’t remember was also very good.
Another vote for Wodehouse get a collection of some of his short stories. Absolutely worth it.
And when we were little, my parents would read Patrick McManus out loud to us. For well over half the stories, my mom would end up laughing so hard she would start crying and lose the ability to speak.
I’ll second Illegal Aliens. Another book in the same vein is Glory Lane by Alan Dean Foster.
Brain Droppings - George Carlin
Swords of… featuring the dynamic duo of Fafhrd and the Grey Mouser - Fritz Leiber
Bill the Galactic Super Hero series - Harry Harrison
L. Sprague de Camp’s Enchanter books
Grunts! - Mary Gentle
Another vote for any Terry Pratchett books and Hitchhiker’s Guide. Also recommend Good Omens by Pratchett and Neil Gaiman.
Kinky Friedman’s stuff, but he isn’t for everyone.
Women by Charles Bukowski. Dunno, always seemed real funny to me after a bad breakup.
I can’t believe no one has mentioned The Princess Bride by William Goldman. Funny as hell.
E3
I’ll second Catch 22 by Joseph Heller. The funny bits are the funniest words I have ever read, while the dramitic war bits are flat-out horrifying. Great, great novel.
I also loved The Princess Bride. Even more than the movie.
I highly reccomend the books of Christopher Moore (Practical Demonkeeping, Coyote Blue, Bloodsucking Fiends, Island of the Sequined Love Nun, The Lust Lizard of Melancholy Cove, Lamb: The Gospel According to Biff, Christ’s Childhood Pal, and the upcoming Fluke.) they are all very funny.
Bill Fitzhugh (Pest Control, The Organ Grinders, Cross Dressing, Fender Benders, the upcoming Heart Seizure.) is very funny as well.
Blackburn by Bradley Denton Buddy Holly Is Alive and Well On Ganymede and Lunatics by Bradley Denton.
The books of James Morrow and Matt Ruff.
The Myth-Adventures and Phule’s Company series from Robert Asprin.
The Xanth books (The first twelve or so are the only ones I feel comfortable reccomending.) aren’t as high on the humor scale as some of the stuff I’ve mentioned, but worth a look.
Harry Turtledove’s The Case of the Toxic Spell Book.
The books of Carl Hiassan
Snow Crash by Neal Stephenson.
Eric Garcia’s Rex series and Joe R, Lansdales Hap and Leonard series are (Relatively, one’s a P.I. series set in a world where dinosaurs live amongst us in disguise, the other’s about a gay black Vietnam vet and an ex-con living in Texas who solve crimes mostly by accident.) serious series with elements of humor.
C.D. Payne’s Youth in Revolt.
Nick Hornby’s About a Boy and High Fidelity
Tim Sandlin’s Skipped Parts, Sorrow Floats and Social Blunders
The Eyre Affair by Japper Fforde
I . . . uh . . . think that about covers it . . .
Oh yeah, Discworld!
Laurie Notaro’s Idiot Girls’ Action Adventure Club was funny. Gerald Durrell’s books from his family’s stay on Corfu are all hilarious (his brother Lawrence wrote some good stuff, but humor was not the point). Bil Bryson’s work is funny, and often laugh out loud good, especially if you’ve you’ve been the places he’s writing about. I also jump on the bandwagon and reccommend David Sedaris.
Donald e west lake makes some very funny books … espically his dortmunder series
but i Havent read anything really funny … amusing yet but funny no …
Another nod to any Discworld book, Hitchikers Guide and Dave Barry.
Also Bridget Jones’s Diary, and its sequal
Well, if he hasn’t found any good funny books since last July, when this thread was started, he just isn’t looking.