I'm building a website in django that needs to extract key words from short (twitter-like) messages.

I've looked at packages like topia.textextract and nltk - but both seem to be overkill for what I need to do. All I need to do is filter words like "and", "or", "not" while keeping nouns and verbs that aren't conjunctives or other parts of speech. Are there any "simpler" packages out there that can do this?

EDIT: This needs to be done in near real-time on a production website, so using a keyword extraction service seems out of the question, based on their response times and request throttling.