As per title, share good webcomics. I'll start, will fill out the well known ones too:
Cyanide&Happyness - Probably one of the most well known ones
Toonhole - Sometimes inappropriate, ever hilarious
Eat That Toast - updated irregularly, but worth it
Three Word PhraseMr. LovensteinRomantically Apocalyptic - Amazing quality webcomic, read from the start
NedroidButtersafeAmazing Superpowers - Don't miss the hidden comics (? at top right corner of comic)
ChannelAteThe OatmealAnticsChainsawsuitSaturday Morning Breakfast CerealRosscott, Inc.Hark, a vagrantGunshow - utter randomness
MS Paint Adventures - More like a semi-interactive super-long story, for when you just got 2 weeks to waste or something
feel afraid - updated extremely irregularly
Yes, i waste a lot of time at work
Also, if you share, mention if it's NSFW, pl0x