I would think that you would need to do it the same way as the censor filter works... if you could specify {bob} like you can in the censored words, then you could replace just bob but not
http://www.bob.com. I would like to do this for multi-word combinations. For example, be able to link {peanut butter} and not have it consider it as 2 separate words "peanut" and "butter".
Could the code for the censor filter be modified or mostly duplicated to accomplish this? It is already evaluating the text when messages are posted...