The web has made it easier for certain groups of people to establish themselves like cartoonists who if they've got a product people want don't need to go through the old hassles of establishing links with publishers and syndicates.
I think a good example is Rich Burlew's Order of the Stick where the success of the online strip has allowed him to quit the day job and make his income from books, merchandise and advertising revenue. Not that it is anything like the income that say a Scott Adams gets from Dilbert, but this is still a niche audience.
Anyway my favorites apart from Order of the Stick are:
DM of the Rings
and not a cartoon and from an author whose work was appearing in print prior to the web Verity Stob at the Register
Quite a lot of other humour sites have developed a bit slowly, e.g. The Rockall Times, which I think is down to the difference between online and print media. Several attempts to do a Private Eye on the web have not entirely worked. I'll return to this theme later.