I'd like to connect my ipod touch (3rd generation) to my ipad2, but I don't see each other through bluetooth. What should I do?

What exactly are you trying to accomplish. You can not "connect" iOS devices directly via Bluetooth. Are you trying to share information between them?

Are you using iCloud?

Also, check out Bump: https://itunes.apple.com/app/bump/id305479724?mt=8

Here is a list of supported bluetooth profiles for iOS:

http://support.apple.com/kb/HT3647

The iOS devices do not have the necessary bluetooth profiles to pair an iPod touch with a iPad 2. There are apps that allow some functions via BT between iOS devices. Here is one.

App Store - Bluetooth FileShare

iPhone: Go to Settings > General > Bluetooth and turn Bluetooth ON.

iPad: Go to Settings > General > Bluetooth and turn Bluetooth.

On the iPad running Keynote, open your Keynote presentation.

Tap the Tools icon in the toolbar.

In the Tools menu, tap Settings.

In the Settings menu, tap Remote.

In the Remote Settings menu, turn on Enable Remotes.

On the iPhone, open the Keynote Remote app.

In the iPhone Settings window, tap New Keynote Link.

On the iPad, the name of the iPhone appears in the Remote Settings window; tap Link.

On the iPad, enter the four digit number that is displayed on the iPhone, and then tap Done.

iPhone: Open the Keynote Remote app. You can begin to control your slideshow from your iPhone by tapping Play Slideshow.