Coming with unique project ideas is always the most difficult task for a programmer, especially when you're talking about platforms where pretty much the majority of applications a user would need have been created. Android market has over 700,000 apps, so it's not really surprising why some people would struggle to think of something new.
Best advice I can give in that regards, is to try and create an application that you want that you can't get anywhere else. Could be anything, like a new concept, or adding features to an existing concept, or creating a more user-friendly interface. If you want it, there's a high chance that other people will want it as well, and it gives you great motivation to actually finish the project. Worst case scenario, if nobody else likes the application, at least you have an application that you've always wanted.
That's why I can't wait for all of the new hardware to come out already (eg. Rift and Leap Motion). New unique hardware always gives me motivation, and I have quite a lot of ideas I want to try out with them.