This is the golden age of online comics, or comics on the internet. So now that you know, you too can walk around and say, "Gee, I'm living in the Golden Age of online comics!" Heh.
But seriously, there are tons of online comics, with more being created every day, and they're almost all free! Of course, they vary considerably in their quality and style, from very crude to animation-style to cgi. Some strips are even made from photos or recycled, public domain art.
A lot of them are humor strips, and many combine humor with science fiction, fantasy, or some other genre. Curiously, I find very few super hero strips--maybe I'm just looking in the wrong places?
Many of the traditional syndicated strips are available online, as well. Check out comics.com, for example. However, newspaper syndication has always been difficult to break into, and is probably harder now that newspaper circulation is dwindling. Most online comics will never be seen on newsprint, although one revenue source for online comics artists is to sell collections of their strips.
Some online comics aren't done in the "comic strip" format of a few panels, but are done as full pages, like an online comic book, one page at a time. Girl Genius is like this, for example, but then it originally started as a real comic book before going online. And creator Phil Foglio has done quite of bit of comic book work in the past, too.
One thing that bothers me, though, is the creative limits most online comics artists place on themselves. Scott McCloud has already done two books and several online stories and articles of his own that explore the limits of comics on the web.
For one thing, why have panels or borders at all? Why not just a set of borderless pictures loosely separated by space (or in some cases, overlapping pictures for compression of time or action sequences)? Why should they even be in a straight line? Or another possibility is simply that each picture is a separate web page, and you click on the picture to go to the next picture.
There's always the possibility of animation, as in animated gif's, but I think if you do that too much, you really have an animated film, and not a comic, or sequential art.
And there are no practical limits on story content. Sci fi, mystery, romance, suspense, historical, humor, etc. As an online comic artist, you are free to tell the story or stories that you want to tell, without editorial constraint. Even adult material, although one still needs to be a bit more careful with putting it online.
So, just remember, we're living in the Golden Age of Online Comics. Enjoy!
There's only a few online comics I keep up with every day (I do have to get some work done for my employer!), although there are many that I check up on every now and then:
Other comics I occasionally check on:
Lost and Found
Mansion of E
Penguins with Baseball Bats
I Can't Draw Feet
Marooned: A Space Opera in the Wrong Key
Silence in the Darkness on Q16
Two Lumps: The Adventures of Ebenezer and Snooch
The Bunny System
General Protection Fault
Anarchy in Your Head
And I come across other new ones every now and then to check out.