I was MOH at a friends wedding a few years ago. I ended up telling the story of their first date (they sort of got picked up by the cops while making out in a restricted area

) It wasn't too embarassing and everyone seemed to get a kick out of it.
If she's pretty sensitive make sure you don't embarrass her. I'd tell some cute story about them that not everyone knows and then just wish them well. Make it no more than a couple minutes.
Look up some versus on the internet. I found a lot of cute stuff by just typing "maid of honor speech" into google.
The most important thing is to have fun. And keep the drinking to a minimum before the speech