Empty application caches and free-up drive space
Purity (formerly known as MacDust) is a simple tool that can empty the caches and logs of a wide variety of applications. If you've ever had a problem with an application not functioning correctly, crashing frequently, and generally malfunctioning, it could well be because the cache or logs are corrupted or damaged. Usually, closing an application will remove most of these problems but not always.
Purity accesses and removes hard-to-get-at files, unnecessary files, and files you might have even forgotten about. Many applications and programs - especially games - are not supported. One obvious omission is Firefox 4, although it's now supported and the developer seems very responsive to user requests.
One great thing about Purity is the amount of hard drive space it can recover - you'll be surprised how much space the caches and logs of various programs take up. If you're running low, Purity is a good space saver. Purity performs the cleaning and space-saving functions that could get your apps working properly again or at least clear some space on your hard drive.