Regardless of whether you're a podcaster who has a separate site for your blog and podcast, or a single site for both, it's always a good idea to draw attention to your podcast. There are many ways to do this, but one of the most obvious is to put a podcast button on the site to attract the eye.
Since nobody has tried to standardize the podcast icon yet (wait for it!), there are a variety of icons out there to use, or you can feel free to make your own. If you're lazy like me, however, you'll be looking for a ready-made solution. Enter Tim Madden's podcast logos.
Personally, I'd like to see a bigger icon to draw the eye than the ones on this page, but they make for a good starting point.