If you want to spice up your podcast a little you can try some of the following:
Speakerphone, or some other kind of speaker emulations. Let your voice sound like it’s coming through a telephone or a walkie-talkie for instance.
Sound effects can be interesting to through in the mix. There are plenty available here at Audival which you can download and use for free.
Play with the speed / the tape machine effect. For this you’ll either need to use a tape machine (duh!) or have some kind of effects processor.
These are just a few examples I could think of. Of course you’ll need to put them in the right context. Using a sped up tape effect in the middle of a discussion of third world poverty might not be the best thing to do (although, a little funny).