Viewing pictures on iPad from Mac server gallery-style
I have tried several apps/servers but most of them are either not user friendly or have limited functionality. 
AirPics (yellowbek.com/airpics-app/) is limited to stream iPhoto and Aperture. Not user folders.
AirPhotoServer (www.airphotohd.com) too much bugs in server app, just poorly written piece of code.
PhotoStreamr (http://www.photostreamr.com) is working, it does fulfill the requirements, server app has some nice custom settings like user folders, password protected private folders, internet access (from outside of home network). iPad app is ok, just ok, you can feel here and there that user interface it is not polished to perfection, but functional part is perfect.
Unfortunately these apps are not updated often.