Not science at all
I won't even both linking to "Consciousness: The Inside Story," which is produced by the Maharishi University of Management, the transcendental meditation (TM) people. TM might be a helpful relaxation method, and most of us can certainly use a bit of relaxation, but it has nothing to do with quantum physics (at least, nothing more than anything else in the world). What they have to say about neuroscience or consciousness isn't science, either. All this is probably best left to a Skeptics' Circle contribution.
"The infidel guy show" (iTunes) is a mixture of all sorts of things, including some science, but also lots of other stuff, mostly skepticism about religion. The detailed information about it in the iTunes Store lists it under "Religion & Spirituality", so I don't know why it is under "Science" in category browsing mode.
For some reason, some local radio weather forecasts are classified under science. These include the "K8 WeatherTALK Podcast" and the "Kansas City Weather Podcast".
The "MAKE Magazine Podcast" (iTunes) has a strange title; perhaps the folks who added it to the iTunes Music Store messed up. It's from O'Reilly and Associates and focuses on seriously geeky software development. An interesting tech podcast, but it's not science.
Low signal-to-noise ratio
I like to talk as much or more than the next guy, but that doesn't mean I like to listen to other people nattering on.
"BeachCast" (iTunes) has some science content, mostly things like interviews with volunteers at a marine mammal care center. I thought about putting this under "not science," but there is some science there. If you like more personal podcasts and aren't searching for a lot of real science content, then you may like this. (You can tell I got a "good vibe" about the people making this and wanted to say something nice about it. Not really my cup of tea.)
Because there's only so many minutes in a run, I don't subscribe to these. They're not bad, they just didn't make my cut to be added to my iPod.
"Singularity Podcast" (iTunes) is focused on answering emailed in listener questions and current events in physical science. Fairly basic information (that may be good or bad, depending on your preferences).
The Great Lakes Radio Consortium (formerly part of US public radio) produces the "GLRC.org Weekly News Report" (iTunes) focusing on environmental news, with some regional emphasis on the Great Lakes region of the US (Michigan and Ontario primarily, it seems). Very much a professional-quality newscast, which means lots of short segments.
"Radio Frontier Channel" (iTunes) is quite interesting. It's a mixture of shows about science and shows about scientists (interviews, not historical). I have provisionally subscribed to it, but I suspect that I won't listen to it very often because of its length (seems to be typically an hour long).
"Regulus! The Astronomy Newsletter" (iTunes) is for amateur astronomers, talking about what can be seen in the night sky. If I were an amateur astronomer, I'd be more interested in this. Maybe when the kids are older and stay up later? Who am I kidding, by then they won't be interested in star watching with their old man.
"Sciencecast.net" (iTunes) is an amateur science podcast from Germany (in English). It's not clear to me how much of the commentary is from personal knowledge and how much is read from other sources. Part of that feeling may come from hearing someone talk in a second language. It also includes snippets from radio shows and podcasters from around the world. In my opinion, those inclusions could be more selective. A good portion of the content is really tech, rather than science.
"Skepticality - Science and Skeptical Thought" (iTunes) interviews people like The Amazing Randi and Phil Plait at Bad Astronomy. Not in my core interest area, maybe a bit long at around 45 minutes per show, and uneven in terms of first-person expertise, it's unlikely to stay permanently in my subscription list.
"This week in science" (iTunes) is similar to Slacker Astronomy, but with a broader scope. It's recorded from a radio program, with phone calls from live listeners. The biggest effect of it being a radio program is time overhead and chattiness. I want to like this show more, but there's just too much extra talk.
"Wanhoffs Wunderbare Welt der Wissenschaft" (iTunes) is in German, despite being listed in the iTunes Music Store as being in English. I put it here as an act of faith, as it is from the Fraunhofer Institut, which are well-respected research institutes in Germany.
The good stuff
To make my cut, shows had to have a high information-to-time content. Here they are, in no particular order.
From Canada, there's "Quirks & Quarks" (iTunes), CBC Radio's Weekly Science Radio Program. It covers all sorts of topics, usually including university faculty and listener questions in at least part of the show. The also have a weekly email newsletter.