afaik there isn't really an alternative homebrew net browser as such ..the recent release of chrome for PSP isnt actually a browser more like a skin with a redirect to an online web browser

other alternative is to use pspkvm its a PSP JAVA mobile phone emulator with it you can run OPERA MINI 4 mobile edition like you would use it on a mobile phone but it works on your psp with the pspkvm emulator

not brilliant but its free and it works