[pickthecrowdup]

Ok. I am using a free trial of Pocket Tunes 5.0 and it has an "auto bookmark" feature that will, obviously, set a bookmark in an audiobook or song when you change to a different book or song.

From the site:
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"15-4 Auto-Bookmark Feature -
Pocket Tunes has an auto-bookmarking feature to automatically create bookmarks for you. When this feature is enabled (see the previous section for details on how to enable it), Pocket Tunes will automatically create a new bookmark whenever you pause playback and open a new audio file.

For example, if you are listening to an audiobook, and you wish to play a music file, but you want to remember where you left off, follow these steps:

If auto-bookmarking is not enabled, then enable it.
Press the center button or tap the pause button to pause the playback of the audiobook.
Press the left soft key or tap the "Choose Songs" icon to select a new song or playlist to play next.
Pocket Tunes will automatically create a bookmark for your audiobook.
When you wish to return to listening to your audiobook, follow these steps:

Select the "Bookmarks..." item in the "Tools" menu.
Select the bookmark for the audio book that you wish to listen to.
Press the left soft key or tap "Go"."
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The software isn't bad. I might just buy it. I wasn't impressed with pTunes 4.2, but I like 5.0. Plus, it plays aac+ and you can sync it with iTunes! Album art and all! As far as I know, this is the only software that will allow you to sync to iTunes. To do so you need to install "Pockettunes sync". It's free and is included in the PocketTunes install package as an option. That's a big deal for me since I add music to my PC via iTunes and that's where all of my album art is. iTunes album art isn't always compatible with WMP.

Good luck!