The folks at Rexwireless have updated their task management software for Blackberry - it now has a number of GTD and Covey features that are worth a look. I'v been using the new version for a few days now and am finding the new features quite powerful and easy to use.
They also have an "idea and note" software package called Ideamatrix that is interesting. I have not tried Ideamatrix, but it may also be worth a quick look.
Info is available at http://www.rexwireless.com/