A quick update, Pontiflex Library for Basic4Android is released here.
Sign up ads are something that I have been waiting for from Leadbolt and Airpush, but they have delayed their release for so long :( I hope Leadbolt will release theirs soon!
Quite an OK revenue source actually this one. Just that their inventory is quite lacking, and does not cover many countries. But give them some time, and I am sure they'll be growing (and 2012 is gonna be THE year for mobile advertising!)
Give the library a spin yo!