I had a texting app I accidentally deleted after I synced my phone. I want it back, but I can't remember the name.
You could change the background. For example, mine was a volleyball game tinted orange. The message bubbles I sent were orange also; I think they changed depending on the backgrond you chose. You could also change the vibrations/sounds for an individual contacct if you wanted. If you have any guesses or anymore questions, I'll do my best to answer them, but I can't really remember much.