Here's a few to try/consider:
Onyx - an OS X utility which allows you to verify the startup disk and the structure of its system files, to run miscellaneous tasks of system maintenance, to empty various caches that may be taking up valuable disk space, to configure some hidden parameters of the Finder, Dock, QuickTime, Safari, Mail, iTunes, login window, Spotlight, and many of Apple’s applications, to delete caches, to remove a certain files and folders that may become cumbersome, etc. Not on the app store. Free from:
http://www.titanium.free.fr/viewtopic.php?f=15&t=1667
Temperature Gauge- If you are using SMC fan control you might want to monitor temperature of various components. Don't get the pro version as it's only advantage is to control fan speed (which you already have).
Memory Clean - tells you how much available memory you have and will flush your RAM with a single command, freeing up space that may have been previously used by other apps.
The Unarchiver - a great tool if you work with compressed archive files. It opens all the most common archive formats as well as older formats (such as StuffIt) and can also get the data out of other kinds of files, including some Windows .EXE installers.
ClipMenu - makes copy-and-paste more powerful. It allows you to manage your Clipboard history, enabling you to select which of your recently copied items you want to paste elsewhere.
http://www.clipmenu.com/
Caffeine - installs a cup of coffee icon shows in your Menu. Toggle this icon to prevent your Mac from going to sleep when there's something you want it to do. Toggle it again to allow your Mac to sleep as normal.
http://lightheadsw.com/caffeine/
AppCleaner - to uninstall apps. It doesn't just delete the app, but also space-eating files associated with the app, such as caches and preferences.
http://www.freemacsoft.net/appcleaner/
