During the ten days I had my wifi iPad, one of the apps I bought is cogs HD... Cool game. Now that I have my iPad 3G, and I've synced it, all my apps are back except that one. How do I download it again without paying a second time?
If you select the app in the appstore and go through the process of purchasing it again you will get a message as it downloads saying something along the lines of 'this app has already been purchased so you will not be charged for this download' - thats what happens on the iPhone / Touch anyway...
Alternatively you can download it through iTunes by selecting Store>Check for available downloads and then sync to your iPad...