Some of you might freak out at this next one: A friend of mine is currently DM'ing a "Hanna-Barbara" d20 game.
It's not strictly Hanna-Barbara - there are Thunderans running around, as well as Paxons (think 3-dimensional Pac-men). There are also Bird-Men, various Herculoids creatures, and EVEN Skeletor and Evil Lynn running around as main villains.
The scary part is - the rules he came up with aren't bad.
I currently play a Paxon Priest, by the name of Adams. (Kudoes to anyone who can find for me the actual name of Douglas Adams' little signature green guy.)
We have smurfs in the campaign, who can become quite powerful enchanters. One player in our group runs a smurf, who rides in a little smurf-sized hot air balloon basket underneath me, thereby increasing his move rate, and at the same time bolstering my defensive capability.