Have you considered using https://appsocial.ly ? They can really help increase downloads and sharing right within the mobile experience.

[Disclaimer: I mentor this team through 500Startups.]

It depends on exactly what you are looking for... This is a pretty open ended question so it's impossible to give a solid answer without more information.

This certainly won't be the answer you expected. To some extent, it's self-promotion; but I'd sincerely recommend thinking about it, since it's the biggest bang for your buck I can imagine. Also, it's time-sensitive:

I own AppDevelopers.net. As a matter of fact, it's in a Flippa auction that ends in roughly 10 days (from October 3).

The average cost per click to advertise with Google AdWords in search results for "app developers" is over $22. Per click! And there are nearly half a million Google phrase searches per year for "app developers".

Given that the .COM is already gone, AppDevelopers.net is the best property left for branding and lead generation.