The following questions are often asked at answers.yahoo.com or ask.com and other ask&answer sites.
How can I transfer my iPod to my iTunes?
How do I copy all my music from iPod to iTunes?
Can I Sync my Old iPod to my new iTunes?
How to Transfer songs from iPod to iTunes?
How to copy my playlists from iPod to iTunes?

Note: If you want to transfer iPod files to Computer , refer to the following tutorial:
How to transfer files from iPod to Computer ?

Now I share the perfect solution to such questions.
You only need an iPod to iTunes Transfer Software.
Click to download this iPod to iTunes Tool

Take the following steps to transfer iPod to iTunes.
Tip: Please make sure that your iTunes is closed when you use AVCWare iPod to iPod/Computer/iTunes Transfer.

Step 1: Install and run iPod to iTunes Transfer.

Step 2: Connect your iPod/iPhone to your computer via USB cable. After done, the iPod/iPhone icon and its library and playlists will appear in the Device list.

Step 3: Open the library/playlist that you want to export files, and then check the file(s) you want to export in the file list.



Step 4: Click the Add to iTunes button to start exporting files.

Tip: When AVCWare iPod to iTunes/Computer/iPod Transfer is started, it will modify the automatic synchronization of music/video to manual synchronization between iPod and iTunes.