Well they dont have the specific webcomics, but they got summaries that describes what's going on in the comics. the site is
http://www.uncannyxmen.net/db/issues/the site doesnt have all marvel comics, just stuff that's mainly tied to the x-men. the site also has summaries on the characters, family trees, and the in-depth history of the more main characters, some are newer than others.
there's also:
http://www.popcultureshock.combut that's only previews, idk if they keep full webcomics, i guess you would have to explore the site more.
(I stole this answer from YAHOO)
I pretty sure you can download them, I think as torrents...Bitcomet and Utorrent