Search4RSS.com has added streaming podcast capability to it’s free RSS service. Once logged in members can browse or search the podcast directory for finding, rating, previewing and listening to full podcasts online. This is more suitable for broad bandwidth connections although it is possible to listen using dial-up modems if you can put up with the jerkiness.
Update: The new Podcast Jukebox feature lets you stream podcasts from a playlist and provides direct downloads of the mp3 files. This is ideal for previewing shows before downloading large audio files.