I have a simple, custom rolled chat here: ( [link=http://ninjawars.net]http://ninjawars.net[/link]
One thing (lowest level of protection) that I have already implemented:
Ignore consecutive duplicate messages from the same user.
Other ideas that I have:
Add consecutive messages from the same user together, instead of creating a separate message line. (relatively simple to implement, decreases the effect of spam but doesn't prevent it)
Prevent continued messages after a certain number of consecutive messages from one user, for new users. (relatively simple to implement)
Chat moderation by trusted users (complex to implement).
Prevent multiple consecutive messages from new users.
Are there any simple methods/systems/algorithms to prevent chat message spamming that I should know about?