One thing I have found since starting the podcast is that sometimes I just can't synthesise or recreate a sound effect to my satisfaction - that's what full-time sound designers are paid the big bucks for (assuming they ARE paid big bucks, that is). There's a wealth of stuff out on the internet, some free and some very expensive, with little assistance in distinguishing between the two. My preference is to go with Creative Commons music where I don't have something of my own that will fit the bill, but often the stuff I want to use has a non-commercial or no-derivatives licence. There are quite a few sites offering royalty free music, but most of the ones I came across were either needlessly complex, hideously expensive or only offered music on CD or DVD.
Audiobank.fm seems to be a little different, with easy to navigate categories, a pretty wide variety - not just piles of electronic breakbeats - and per-track pricing, meaning that if my podcast only needs one short snippet of polka, then that's all I pay for. Prices are around the $10 mark - high in comparison to most online music shops, but quite reasonable for a lifetime of royalty-free commercial use. They also do their own Reason drum kit with a range of 15 different kit styles using 24 bit samples.
Certainly worth a look if you're on the look-out for jingles for your podcast.