Like downloading or reading Free Comics ... legally? Here's some places to go where you can read or download comics without spending a penny.
http://www.ninjaturtles.com/ - The official site of Teenage Mutant Ninja Turtles. I'm not a fan of the Archie series, or the cartoons, or the movies, but I did enjoy the original series that started it all, and if you head to this site, you can read the first 17 issues of TMNT, plus five one-shot comics.
http://www.elfquest.com/gallery/OnlineComics3.html - ElfQuest.com says it has every single ElfQuest comic available on its site, dating back to 1978.
http://marvel.com/digitalcomics/free - Marvel Comics website features some comics you can read for nothing. I haven't checked-out their site for a while, but it's nice to know that with 70+ years of publishing under their belt, they haven't changed their selection of free comics in a long time (that was sarcasm, by the way).
http://www.imagecomics.com/onlinecomics.php - Image Comics has almost 40 comics that you can read for free. That's not a huge selection, but ... well ... it's free!