A few comics I really enjoy that I haven't seen featured in this thread are these:
Weesh -
http://weeshcomic.com (updates MWF)
^This one is about a trio of siblings and the green-rabbit-wish-granting creature, named Weesh, that lives with them and their dad. Weesh can only be seen by children (or those that are kids at heart), and all he needs to grants wishes is licorice. An absolutely hilarious webcomic, especially with how wacky the two youngest kids' wishes can be. It's also clean and can be shown to kids of any age.
Kimono's Townhouse -
http://kimonostownhouse.com/ (updates MWF)
^Essentially, the main characters, Kimono and Minty, are ponies living in a townhouse together as roommates. Kimono is a cultured, quiet, refined pony that works at the library, while Minty is a geek girl that works at customer service for an Internet provider and plays D&D. Rather than being hand-drawn, this comic breaks the mold by being photographs of actual MLP toys the author owns, and all the props are dollhouse props and various things brought in or made for the comic.
Angel Moxie -
http://www.venisproductions.com/angelmoxie/ (finished a long time ago)
^Drawn by the same artist that does Weesh, this is both a parody of magical girl anime and a delightful story in and of itself. Essentially, three girls are shown to have the three heroic powers - strength, wisdom, and magic - and they have to stop the villains from resurrecting a powerful demon. The story gets a lot more complicated and epic than that, though.

Fragile -
http://www.fragilestory.com/ (updates TTH)
^A relatively new webcomic I discovered not too long ago, and it just barely finished its first chapter. Thus far, the story is about the timid Marian and her friends, as well as Marian deciding to try photography. It also features a new girl in town name Emily that, after two unfortunate encounters with Marian (one of them involving a camera and a load of misunderstanding), hates Marian with a passion. As the story is new, it's still working on developing the characters, but the art is still lovely. I recommend giving it a go, and there's even a way to receive email updates whenever the author completes a chapter, which is good for those of you that dislike waiting for individual pages.
Erstwhile -
http://www.erstwhiletales.com/ (updates MWF)
^This is the result of a group of artists that retell Grimm fairy tales in comic format (and one of those artists is the same one that writes "Red String"). They focus on stories that are obscure, and they're beautifully drawn and told. Thus far, the tales they have completed are "The Farmer's Clever Daughter", "A Tale with A Riddle", "Maid Maleen", "The Bird, The Mouse, and The Sausage", and "All Fur". They's recently started "The Little Shroud".
That Deaf Guy -
http://www.thatdeafguy.com/ (updates weekly on Fridays)
^This is about a Deaf man, his hearing wife that's an interpreter, and their hearing son. I adore this comic primarily for the insight it gives into living as a Deaf Person or with Deaf family. I believe that's something all of us hearing people need to see. It's also a really hilarious comic, and it resembles newspaper comics in format and continuity.