Okay, Polarity's been completed, That was recommended a bit higher up on this page,.
Now for some new Recs.
First off:
Spiderman: Reborn (Spiderman)
http://www.fanfiction.net/s/1363189/1/Spider_Man_Reborn
COMPLETE. Pretty Solid Spiderman Fic, Retelling the Mythos in a very interesting way. Specifically, with one pretty important change to Peter Parker's Origin Story. Someone other than Uncle Ben gets killed. The Series reads a bit like the Ultimate Marvel Reboot in terms of Stylistic changes to the mythos.
The Portal (Smallville)
http://www.fanfiction.net/s/1059069/1/The_Portal
COMPLETE. With a Sequel that's also Completed and another sequel that's active. Lana, Lex, Chloe and Clark get thrown through a Portal into ancient Rome and now they need to get back. A pretty interesting take on Superman. There's a lot of surprising stuff in there and I don't want to Spoil it.
Thick As Thieves (X-Men)
http://www.fanfiction.net/s/547730/1/Thick_as_Thieves
COMPLETE. With a Sequel that's Active. Iceman Follows Gambit to a Club and Falls in love with a Girl there, unfortunately, she's married to a member of the Thieves guild. So Iceman goes to Gambit asking to be trained as a thief in order to get the girl. A really good fic focused a bit on the limits and potential of Iceman and Gambits powers. Lots of Character Building, and Some fun action scenes.