Port Haiku API to other platforms and get more native apps
A great way to get more app developers to Haiku is to port the Haiku API to other OS'es. Gobe actually already did this with the BeAPI, but unfortunaly the source code isn't available, but it shows that it is in fact possible.
The big hurdle for app programmers is that Haiku is a very small OS and hardly anyone has heard of it so developing Haiku exclusive apps isn't really an option when they can get way more users on other platforms. But if it's was possible to really easily to port to other OS's then they could use Haiku as their development platform making native apps and then port to other platforms without any big hurdle. It's much better if the apps programmed on Haiku first and then ported to other OS'es than the other way around. This way it dosen't matter if Haiku is a tiny platform as long as it easy to develop with it and port apps from it.
This solution, combined with finishing porting Wine to Haiku, is a much better way than trying to port individual apps to Haiku.