I've discovered a great way to increase Japanese reading speed -- Japanese karaoke!!! It's a real challenge for me to be able to read fast enough to sing any normal to high-speed songs, but it's fun and I'm finding that I'm slowly getting faster and faster at it.
(...Of course, I've also gotten better at finding and picking the songs despite the massive amounts of kanjified names. I can find and select at least five songs in under thirty seconds now... And I usually do.
)