You can make you iPod beep and have the number of new e-mails pop up on your mail icon. This is done by going into ‘Settings’ > “Fetch New Data” (Under Wi-fi tab.)

Now turn off “Push” and change the “Fetch” to your desired update time. At the bottom of the page there is a tab called “Advanced” Go into that and your e-mail addresses should appear. Make sure they are on Fetch and not manual. To change them simply tap the address and select Fetch.

Now when you receive an e-mail the iPod will beep and display the number of unread messages on the mail icon.

Go to Settings
Then go to Fetch New Data
Turn Push Off
Choose how frequently you want it to Fetch your information (new mail)
-Every 15 Minutes
-Every 30 Minutes
-Hourly
-Manually
Just don’t choose manually

Just a little note, like any other program on the iPod Touch that uses Wi-Fi, turning the Fetch feature on will kill your battery faster. So having it done at bigger intervals (such as Hourly instead of Every 30 Minutes) will make the battery last a little longer.