Text-speak
As far as I can see the only place where you are going to get to use standard Japanese is most likely a forum where the speakers are non-native speakers or people learning the language. I would think in that case the Japanese used would be closer to what you would understand, therefore something like the Nihongo forum is more suited to someone who is learning.
A fourm where the main users are native speakers will use slang, as they would assume that other users have the same language abilities as they do and also understand the cultural subtext. The best way, I can see is to probably start a thread similar to (url).
Kyoko-sans English is very good, but she doesn't always follow English slang. Something similar would help you become more familiar with Japanese slang so you could then participate in the Japanese fora you wish to post in.