I'm getting into it too.  The big thing you learn is - if you always have a P&S camera in your pocket, and you try to develop the habit of looking around you, you'll find interesting pictures.  But I often end up regretting I don't have my DSLR with me.

Unfortunately the camera in my smartphone (HTC HD7) is absolute cr@p and not even in the same galaxy as the iPhone camera, so none of the photos are good for anything other than posting on FB for my friends.   Once in a great while I  follow up later with the DSLR.

Yeah, I know what you mean about not having your DSLR when you see a great shot.

I'm not sure what kind of apps you're looking for but for creative artsy photos PicsArt is really cool. Plus I'd suggest a file manager so you don't have to plug your phone into your computer in order to access whatever's on your SD card/phone. Also Color Note comes in handy a lot, as well as Mr. Number which is a caller ID which tells you who's calling if they're not in your contacts.