I really enjoy RussianPod101 for learning in my car. I just wish it were easier to navigate on my iPod. I've been subscribed now since June 2008 so I have a massive collection of files. At my computer, using iTunes, it's easy to find the subject and levels that I am looking for. On my iPod it's a nightmare.
Have you ever considered splitting the feeds so that all advanced would come under RussianPod101 - Advanced, all intermediate RussianPod101 - Intermediate, etc? This would improve things a lot at the listener's end. I have no idea how much of a pain that might be at the provider's end though. But I hope you will at least consider it in the future.