I have jumped on the "Yak-On" band-wagon
it is GREAT
i like it better than ramble and i reccommend it to any BB user
also...they have GREAT customer care! I had an idea that i emailed them and they liked it as well and added to their beta version which will fully launch this year - and u can download the beta at yak-on.com/beta i believe
give it a shot before u buy the license and i seriously think u'll love it!
there are even tabbed IMs!
but Ramble is awesome too i used the pre-loaded program on my friends 7105 and wasnt in love with it - i have ramble and yak-on loaded on my 7100i - try either one