Again... until someone modifies the firmware to support packet capturing will we be able to consider this project. Simple porting of an application cannot work successfully unless you have the access to the packets in the first place, which is exactly what we don't have right now. People are getting the wrong idea by this. If it were so easy or even possible as of now a prototype would have already leaked.
A port of firefox would be interesting, although I suppose due to the PSP's RAM limitations common features such as plug-ins and extensions would have to be pulled from it.