You most likely have never heard of Aerize (nor have I) - but they have released three great apps that look to be a step in the right direction. The most exciting is Aerize Card Loader 2008 which lets Blackberry users install applications from an SD card in a few easy steps. This is really a major step for BlackBerry users with memory issues. You can keep your collection of mildly/infrequently used apps on your memory card (the ones that don't warrant a full time install) and install them on demand. For more information, take a look at the Manual (pdf). The Card Loader 2008 is $20 and a free trial is available.
Aerize also has Aerize Explorer 2008 a simple zip/unzip utility, and Aerize Optimizer 2008 which is a memory cleaner/booster. I played around a bit with the Card Loader app and so far it seems to do most of what it claims. If you have a lot of apps to put on an SD card, this is the way to go as it keeps your device memory free for optimal performance. They have 7 day trials available for each app, although I couldn't seem to get the Optimizer to run as it kept asking me to enter a reg code. All in all some good stuff here from Aerize available here.