To deal with this, I sometimes visit their archive page, use Firefox's Aardvark extension to print a nice copy of the descriptions of recent shows, go through these with a red pen and identify which I really want to listen to and which to remove from my iTunes/iPod using ipodder's cleanup pane. Since this is a little too much work, I've come up with two ways to change this process, one that I can do now and one that requires a change to ipodder.
The one feature that ipodder lacks which would make this process easier is a way to show the text associated with each feed entry. IT Conversations includes a paragraph with each describing the speaker and the topic, Coverville includes a playlist. With this, I could designate which shows to cleanup from within ipodder. Alternately, I could designate which shows to download in the first place.
Since this feature doesn't yet exist, I'm going to opt for the other option -- don't download IT Conversations podcasts with ipodder. Instead, I've subscribed to their RSS feed in bloglines and when I see the description of a show I want to hear, I will click on the "enclosure" link and save it using iTunes. I fear that this won't be a simple as I think it could be, but I'll try it for a while.
(Yes, this is another case of a user of an open source product whining about a missing feature that I could probably add myself if I put myself to the task. However, I don't have the time to do so this month. I promise to donate to the project if it gets added by another person, though.)
I've got some thoughts to post about other podcasts I'm listening to, in the meantime, if you'd like to see a list of what I'm grabbing, see the "Podcasts" portion of my blog roll.