I only read a few online comics. A new one which has made my RSS Feed list is Misery Loves Sherman. It’s got a little bit of a Calvin and Hobbes feel to it, but it isn’t trying to be Calvin by a long shot. The strip is done by Chris Eliopoulos who has had a pretty amazing career in comics. From lettering The Savage Dragon (which I had completely forgotten) to doing the hilarious Franklin Richards: Son of a Genius.
Read the New Readers section and get started. It’s good stuff.