For newer stuff, monthly updates and that kind of thing, The Pirate Bay tends to be the most popular. h33t is also pretty good for getting big collections. I only started reading comics in January-ish, but I tend to dive into things headlong, so I've read a lot since then. ^^;

If you're especially interested in Tony/Pepper, the new Iron Man volume 5 issues are leaning very far in that direction. ;3