I found that tht my N900 fits in perfectly to my Blackberry Bold's official case which has a rotateable belt clip. It was perfect for my holiday to Egypt last week.

http://www.mobilefun.co.uk/blackberr...004-p17727.htm

Obviously it was never designed for the N900 so I'm not sure if the headphone jack is useable. I had a strap on my phone, so I had to put it in the case with the headphone jack downwards, so no access that way.

Since coming back, I've got a case without a belt clip which just about gives access to the headphone jack. It's a Krusell case:

http://www.mobilefun.co.uk/krusell-c...ack-p21807.htm

It has a belt loop, and I don't push it all the way in if I need to use a wired headset.

If you have a belt, I would definitely recommend the Blackberry Bold case. It's perfect, especially if you have a bluetooth headset/headphones.

If you also have a strap on the left hand side, it makes it easy to get out of any case quickly.

PS. I'd originally wanted a CP-321 but after finding out there was no access to the headphone slot, I found the Krusell. I already had the Blackberry case for my Bold, so obviously that was not an extra cost for me.