Well here are the ones I know: 
Title: A Wizard Escapes 
Author: Hubristic Chick 
Link: http://www.fanfiction.net/s/4430051/1/ 
Summary: Harry James Potter has survived the War...but is now alone. He is the  Magical World's Hero...but for how long? When he turns 21,Harry comes  into his full powers and the wizarding world turns its back. AU after  Book 4-Crossover with X-men SlashHarry/Gambit 
Rating: M 
Length: 10 chapters (26,698 Words) WIP 
Title: Wolfeli 
Author: amycakes 
Link: http://www.fanfiction.net/s/2997219/1/ 
Summary: Thinking back on it, wandering into the forbidden forest at night  really wasn't a smart thing to do. Exiled, alone and in America; Slash  and all that good stuff. xmen xover H/L 
Rating: T 
Length: 17 chapters (19,683 Words) WIP 
Title: The Thief and the Wizard 
Author: dragonscales 
Link: http://www.fanfiction.net/s/4759609/1/ 
Summary: After Gambit is left to die in Antarctica help comes in an unexpected  way. Harry Potter was on a job to retrieve an artifact from an old  wizard stronghold when he ends up saving a strange man from the ice and  snow. What does the future hold? 
Rating: M 
Length: 6 chapters (13,809 Words) WIP 
Title: Second Chances 
Author: spidergambit 
Link: http://www.fanfiction.net/s/4465224/1/ 
Summary: Harry has finished off the Dark Lord and left the wizarding world to  start a life of his own. HP/x-men crossover. No pairings as of yet. 
Rec Note: good chance of slash 
Rating: T 
Length: 10 chapters (22,863 Words) WIP 
Title: new life 
Author spidergambit 
Link: http://www.fanfiction.net/s/4561123/1/new_life 
Summary: A Harry Potter leaves the wizarding world after he defeats Voldmort.  Believed dead by everyone except the goblins he lives in selfimposed  exile until a chance encounter with the xmen. Harry/Gambit slash. You  have been warned 
Rating: M 
Length: 11 chapters (69,786 Words) WIP 
Title: Of Slings and Arrows 
Author: the original Pe 
Link: http://www.fanfiction.net/s/2145218/1/ 
Summary: Harry potter has been thrown into Azkaban for a crime he did not  commit, and then rescued by the strangest ppl. A journy to belong. AU  begins at the end of fourth year, HPXmen evo crossover COMPLETE! Pre HBP 
Rec Note: If I remember right this is HP/OFC 
Rating: T 
Length: 41 chapters (86,542 Words) COMPLETE 
There's more, but those are the ones that I can remember.