Most podcast episodes run close to an hour, and some (including some of the most popular) run 90-120-150 minutes, and single episodes of some can run even longer! But there are some good ones out there whose episodes regularly run less than 10 minutes each. Some of my favorite of these cute little podcasts include:
Grammar Girl's Network. Mignon Fogerty started her Grammar Girl podcast years ago, producing weekly 5-minute episodes on all parts of language usage, writing, and grammar. She has grown her network Quick & Dirty Tips since then to include similarly-formatted shows covering legal, health, organization, and other topics. The two that I listen to, in addition to Grammar Girl, are Money Girl and the Winning Investor.
Tom vs. _____. Tom Katers has put out consistently entertaining episodes since he decided to summarize early issues of the Justice League comic book in his Tom vs. the JLA. Since then, he knocked out more than 150 episodes/issues of Tom vs. the Flash, before moving on to his current project, Tom vs. Aquaman. Tom loves these early issues, but is more than wlling to point out when the silver-age silliness goes over the top.
The Dennis Miller Show. The full re-broadcast of Miller's daily radio show costs money to subscribe to, but they post a handful of short segments every day as "previews" through iTunes. The opening segment of the show, which is about 10 minutes long, is available every day, as are most of the interview segments of the show, which usually run 6-10 minutes, although a few do go longer.