I just discovered Secret Acres this past week and really am loving what they do. They are serious about promoting independent comic projects as well as showcasing a number of great artists.
If you enjoy underground comics at all, you should definitely check out this website. There is a load of free content in addition to the ability to purchase (at reasonable rates) actual comics.
While I have not been browsing the site long enough yet, it appears that they update new comics fairly regularly.
Seriously, check these guys out: Secret Acres.