.. take an idea from the Garry's Mod forums.. and add a feature that docks you credits or something for horrid spelling or grammar, but if the user fixes the errors they get the credits back.
The feature helps there a lot, but they use an "IQ" system. When you sign up you have ~5000 points, the more poor your grammar/spelling, the more those points drop. The further they drop, the less you can do (even stopping you from being allowed to post outside of off topic forums). It helps them a lot because people actually fix their mistakes and talk in a coherent fashion, resulting in less headaches deciphering "leet speak."
Though, sure, it might hurt those people who aren't the best in English to start with, such as those from other countries where English is considered a second language. But, it may help them learn spelling and grammar as a result.
Just a suggestion, probably going to get flamed for it but oh well.