Can I do anything to have my iPod Touch (2nd gen) louder?
Directly on the iPod, I don't think so, if your sound settings are maxed.

Try


  Settings > iPod > Volume Limit : Off


and


  Settings > iPod > Sound Check : Off




On iTunes, go to the "Info" window of the podcast audio file, and in the Option tab, try to see if you can set the audio volume to 200%. I know it works on music, but it should also be available for the podcasts.