The useful ness of most apps will depend on what the device will be used for. For instance, if he has lots of bills it might be helpful to get an app that helps him budget for them.
I recently purchased Read it Later which is pretty neat, it lets you save websites so you may read them at a later time. Works great for online info you might need to take with you when you leave a WiFi zone, for instance if you use a website to get instructions to a certain location you can just save the site and view it at any time to help you find it. It can be used for a number of things and it even saves photos if the article you are saving has any. I think there is a free version with limited features. This wouldn't be an App a iPhone user or iPad 3G user would want since they can access the info at any time unless they wanted to save them to reduce their bandwidth usage.