Well I think themed parties are great and are usually a huge hit, I do something different every year and people love it. I recently did a 50's retro themed party and it was great. We had about 10 people, the boys came in leather jackets and combed their hair back and the girls came in like polka dot dresses or poodle skirts.
Now to break the ice we did the best thing everyone got a helium balloon each and we all took turns in inhaling them and speaking in a squeaky voice, it was a riot!
Also we had some great songs playing (not exactly 50's) and that's what really what lifted the mood because everyone was singing along to them, here are some examples of what we had:
Livin La Vida Loca
Bohemian Rhapsody
Mambo #5
Holy Grail
Footloose
and tones more like that that everyone knows the words to.
And lastly we had a small chocolate fountain running which was a huge hit and not too expensive on ebay
So I hope this helps, Good Luck
How about a South Park party or even an American Dad! party?
Thomas the tank engine and Care Bears.
If you plan a theme, focus on what the person really likes.
I wanna have a plan low key party and I'm not sure what you would do, should i have a theme I'm not sure?