This is a list of my favorite and regular web comics.
Tip: Hold down the control key and click each comic link in turn. Doing it that way instead of clicking normally will open a new tab for each one.
Daily or Mon - Fri
Dilbert - One of the most widely read office humor comics, with good reason
The Argyle Sweater - Sort of a Far Side inspired comic, some hits and some misses
XKCD - (Mon,Wed,Fri) Odd humor, often funny math or science, despite how hard that is to believe.
(Mouse-over for extra content, or see the forum or explanations. Also interesting is the Thursday What If article.)
Daily or Mon - Fri
Questionable Content - lots of romantic confusion and anthropomorphic, robotic computers (related: Alice Grove)
Evil Inc. - Satiric business humor meets comic superheros
SMBC - Saturday Morning Breakfast Cereal is mostly shock humor, terribly funny or terrible, sometimes both (red button for extra content)
Least I Could Do - Imagine a twelve year old's ideal man, now pretend he has friends.
Cyanide and Happiness - often funny, often disturbing, sometimes depressing
Wulfmorgenthaler - Often offensive, rarely very funny, but occasionally hilarious
ifunny - the same ifunny you might get as a phone app, along with my own favorites
uberhumor - more funny, not kid safe
evilmilk - more funny, borderline NSFW
9gag - picture dump
Pictures Of Walls - graffiti
Overheard In New York - things people overheard
The Oatmeal - A brilliant and perhaps slightly unhinged look at many things, including grammar
NEDROID.com - there is a pigeon and a bear
Either not turning out new stuff or I'm not keeping up anymore
iFunny - bunch more pictures
Sluggy Freelance - A saga of magic, bad science and a foul tempered lop bunny wielding a switch-blade
TextFromDog - Ever regret teaching your dog to use text messages?
Cow and Boy - Mostly about a talking cow and his friend - no longer making new comics
qdb.us or latest bash.org - Remember that thing somebody said in a chat room on IRC or Yahoo or Google or something? This is a collection of those, sometimes beyond offensive
NikNaks Blog - formerly another funny picture site, now apparently gone
Don't Feed the Geek - Tales from an IT geek with two girl children (no, it isn't me.) - And his struggle as he found and eventually lost a battle with a brain tumor.
Goblins - What if the Goblins weren't really the bad guys?
Girls With Slingshots - Alternate lifestyles, a talking catcus, lots of poor decisions (doing reruns now)
Popstrip - Usually stick figures with a bent sense of humor
I Can Haz Cheezburger - cat pictures with humorous captions
d-lol - a bundle of pictures, not necessarily safe for work or your sense of well being
lolsnaps - more funny pics
Ugly Tattoos - very um... interesting
Daily Haha - another bunch of pictures
Dork Tower - Sort of an iggy meets nerds theme
Basic Instructions - Sometimes men need to be told how to manage the basic stuff in life, this might do that some day (re-runs)
Doghouse - Simple stick figures, complex issues
PassiveAgressiveNotes - what it says on the tin
Ctrl+Alt+Del - Nerd and gamer humor
RaphComic - May be dark
Not exactly comics, but fun (depending on your geekiness)