Did you know that Spider-Man appears in the first X-Men movie? Well, it didn't make it into the final cut, but you can see the deleted scene online at YouTube.
Apparantly it's also available in the DVD version, If you go into the special features menu and click on a green rose in the top left corner instead of clicking on words, you can access it. May require PC DVD viewer to access the feature, you standard DVD player may not allow you to select that feature.