check out www.blambot.com, Nate has some free sci-fi-ish fonts there you might like.
Look at Android Nation, Mars Police, Mother Ship or Botix.
One note tho, you probably want to check with Nate himself before you use any of these fonts for this purpose.

Thanks for the info. Yeah, I saw the agreement and I 'm not too into any of the fonts, so I am still looking.

A

"retro-futuristic" that's all i could think of outside of the suggestions i already made.

I knew a designer once who always showed his clients a diagram with the three words "good, fast, cheap" on it. When negotiating contracts, he would tell them that they could pick two (i.e., they could have their project done good and fast, but then it couldn't be cheap).

I remembered this when I saw your post's title, Alberto, saying that you want a font that is " free, fun, [and] slightly futuristic."

Do you know which one? I've never been quite sure how to choose type for kids, and I'd be interested if you can shed some light on this. My gut feeling is that people tend to "talk down" to kids and choose dopey faces that seem to them, as adults, to have qualities they read as "childlike" and "fun." The educators at our museum, at least, seem always to favor "lively" faces that move perilously toward the comic sans end of the spectrum. Whereas the best designing for kids I've seen is in trade book publishing, where the faces seem in general much more sophisticated. I suppose one gets paranoid about coming off as boring. What do you think?

make sure you read the EULA ... it is very specific about when you CAN and CANNOT use them for free.

fontdiner is also listed on point-central, as is astigmatic and many other great foundries that offer brilliant and fun faces.

I'm going to make a sign of that Dan. I remember that from years ago and had forgotten about it.