Itsudatte My Santa!

Both revolve around the Christmas season, and involve a Santa apprentice character. They both are relatively short and charming, in different ways. Itsudatte My Santa! is for a much more mature audience though.  

Both are funny Christmas specials that are sure to make you happy around the holiday season. Both start with the characters being alone on Christmas and then take the funny yuletide interactions up to 10.  

Similar style of comedy, and level of seriousness. 

Two Akumatsu Christmas specials, not much else needed to be said there :P The Love Hina special is a bit more christmasy, but both focus much more on the holiday than most Anime. 

Both are about an unnormal girl that gets involved in a normal boy's life and changes it forever. Both are very short OVAs, so you have lots of time to watch them both. 

Both anime are cute stories about a lonley boy meeting a very sexy Santa on Christmas Eve. If you like romantic comedies of the Christmas variety, and don't mind a little fan service, then I definitely reccomend "My Santa" and "Miyuki."