I found an Ipod. Now how do I find its owner?

You could put up a "Found" poster in the park you found it.

Just put your phone number and say "found iPod in this park, please call to see if this is yours." Do NOT describe the iPod in ANY way. No colors, no generations, no songlist stuff, Nothing.

Once they call you, open up with open-ended questions without describing anything about the iPod itself:

"can you tell me when you lost it?"
"what color/type/generation is it?"
"if I looked through the playlist, what would be the most played?"

A lot of times people just claim shit that's not theirs if they see it or know what it looks like. If someone's earnestly looking for it, and the true owner does call you, they shouldn't have a problem with the above questions.

Jam it back in, in the dark.