SlimCleaner 3.0 (free) is by far one of the more useful multi-utility tools I've run across. Aimed primarily at cleaning the junk out of your system, it has the capabilities of several popular programs, including Piriform's CCleaner and Trend Micro's HijackThis.
SlimCleaner neatly divides its functionality over seven main tabs/tools: Cleaner, which removes detritus from the registry, temporary files, etc; Optimize, which lets you to edit startup items and services; Software, which lists and uninstalls programs; Browsers, which does the same for browser plugins; Hijack Log, which lists software which might be cantankerous; Disk tools which lets you optimize or wipe disks; and Windows where you'll find all the native Windows utilities in one place and in an arguably better arrangement.
Run any of the above tools and you'll most likely see a list of results: programs that are installed, registry entries that are obsolescent, plug-ins that are present, etc. Every item in every list generated by SlimCleaner has a More info and a CloudAV button next to it. More info tells you everything that SlimCleaner and its online database knows about the item, while CloudAV is an online database cataloging the safety or purpose of each item. I've used such catalogs for years in cleaning malware off of computers. You can easily add information to the databases from within SlimCleaner and the company awards you status according to how accurate and helpful your reporting is.
SlimCleaner worked extremely well in my tests. It found lots of outdated registry entries, accurately reported temporary files, and was aware of a vast number of programs. It's nice-looking, extremely logical in its layout, and largely easy to use.
I'm leaving SlimCleaner installed, and it's a rare day that I make that comment about a utility in a review. It's that handy.
Note: The download here is only 0.6MB but it downloads a lot more stuff; the full installation is about 32MB.