Medieval fantasy can be crossed with other genres to create slightly (or very) different concepts and new aspects. Here are a few I think work well together.

Dragon Riders- This genre is by default medieval fantasy, seeing as that's the only time setting I ever see it as, with the occasional modern fantasy story here and there. It puts a slightly different spin on dragons to normal medieval fantasy, changing their role seeing as most are domesticated in the Dragon Riders genre.

Pirates- Have you ever really taken a modern pirate story very seriously? How can they dress up like Captain Jack Sparrow in any other time period? Medieval fantasy crossed with pirates creates an awesome genre.

Vampyres- C'mon, you know I'm right. Only because I'm not talking about sparkly vegetarian vampyres. I'm talking about the ones I described in the Character Builder. And they can be awesome... when used correctly, and handled with care.

Horror- I love a good medieval horror. Psycological thrillers, supernatural events...

Highschool/academy- An academy for sorcerers to become mages, or a school for the nobles would actually be quite interesting, seeing as medieval education was entirely different and exclusive compared to the modern warfare that is the Highschool genre.

Modern- This crossover can be accomplished using time travel. Trust me, with the right plot and some wacky characters, this crossover can be epic.

Gifted- the most common plot I see for 'Gifted' is "gifteds running from the government" or something which involves 'gifteds' being hunted/feared in some way. So, why not transport this to the middle ages, and see how it changes things?

If you have an interesting combo in mind, drop me a message!