Here's one I wish someone would take from me and spend lots of time perfecting. I've been trying to get around to it, but have other stuff to do. It's on my "fun weekend hacks" list.

I have a commute that's about 30 minutes each way and 1 hour lunch every day. That's two hours I want to fill by reading printouts of interesting text and listening to interesting audio on my iPod.

For me PG essays would be the ultimate example of texts I want to read and Venture Voice (podcast) would be the ultimate example of what I want to listen to (others would obviously have different taste). I've gone through that stuff repeatedly and tons of other similar content, making it difficult to find enough new stuff to keep me entertained.

A site that let me assemble text-printout "playlists" and iPod playlists for a week or more in advance would be great. It requires measuring or guessing how long a given text (or book) is to see how long it would last and organizing the audio into chunks that are optimal for my given time allotments.

It seems kind of a weird maybe or niche, but it arose from a real problem I have and I think it could be pretty big. There has to be more people like me that want really targeted text and audio content to consume on their commute.