I have 40, 1 in the mail (Heros) and 1 on preorder (Top Gun).
Assuming the expected titles are annouced I expect to buy significantly more by the end of the year.
Harry Potter 1,2,3,4,5
Shrek 1,2,3
Oceans 11,12,13
Transformers
Knocked up
Battlestar Galactica
Bourne Ultimatium
and no doubt lots more when they are announced.
Just as I was starting to get a bit antsy about the format the paramount annoucement renewed my faith and desire to buy titles.
I have £1000 saved up now to spend on something I'm not sure where that is going yet though, Possibly going neutral or more likely I think I'll save up another year and replace my 42 inch 720p plasma TV with a 50 inch, 1080p comercial panel that handles 24fps properly.
Quite a few of the regular posters here have very big high def librarys with a couple of hundred titles.
Edit - Err sorry just noticed this is in the 360 section, I followed the link from the frontpage and didn't realise that maybe you are aiming this at 360 add on owners? I do have a 360 but brought a Toshiba E1 for HD-DVD.