I have been considering the purchase of an Instant Messaging App for my Nook but was holding off because of the very few times it would be useful. Yesterday I was using the Internet with the new Dolphin Browser and was being so impressed with it's capbilities that I tried my Yahoo Mobile IM function. It worked very well! Like I said I am not a big user of instant messaging but this will certainly do the job for me.
I installed IM+ Pro and it works pretty well for chatting with my AIM friends.