Eclipse Indigo - Cannot install Android ADT Plugin

Solution 1:

Head over to Help -> Install New Software. Click on Available software sites. Delete the Android repo. Uncheck Indigo & Eclipse updates & recheck them. Now head back to Help -> Check for updates. Once done, add the Android repo again. Accept the license & you should be good to go.

(Had to do the same yesterday after getting Indigo)

Solution 2:

I had the same problem. This helped for me:

1. Go to Help->Install Software
2. Click on "Available Software Sites"
3. Click on Add: Name: "Helios" Location: "http://download.eclipse.org/releases/helios"
4. Try to install Android Development Tools