Good idea, just be careful with the layout. The benefit of apps vs looking for something online is most of the profiles online don't seem to be mobile friendly, making it a wreck to move around. If you can cache profiles prior to leaving your internet access area (assuming you're not on 3g) this could be a good idea. If you want to go for some fish but don't want to remember every detail. As well as poking the heads of people working there if you're unsure about something.
In the future if you incorporate it with a forum so you can browse it easily at a nice format.
At the end of the day, are you looking for a profit from this? Or will it be free? What will truly be motivating you? Since it's something like a database you will most likely have to create your own profiles (Unless you contact a website themselves,eg badmans).
If it's for profit, you're not going to have a major audience unless you target it moreso towards the states. I would look more into what it will cost to setup, how you will be funding it (Donations? Paid applications?) ect. It can be alot of work, think about how you're going to approach these. Not to put you off, just have a good think about this and discuss it with your mate.
I reckon go for it.