I bought a shiny new iPod touch, and after unlocking it to install custom applications, I soon filled the 300Mb applications partition. If you need more than 300Mb for apps (which you more than likely will if you install more than a couple), you can create a sym link to the music partition.

1. SSH into your iPod using a client such as Putty with the iPod's IP address, user: root, password: alpine.
2. Move the applications folder to /private/var/Applications by typing mv /Applications /private/var/Applications
3. Change directory to / by typing cd /
4. Create a link to the new applications directory: ln -s /private/var/Applications Applications
5. Now when you list the directory using ls -la, you should see something like lrwxr-xr-x 1 root admin 25 Oct 12 22:31 Applications -> /private/var/Applications
6. Reboot your iPhone and fill up yet more space with useless applications!

[Via: MacRumours]