Very pleased with Extreme Clean!
I particularly liked the option run it in 'safe mode' before you clean, to see what it's going to remove. There were thousands of old page versions and other bits and bobs of unused blocks on my site, that I hadn't realised were there. My database was half the size once the site had been cleaned, and was performing much better.
The developer is a long standing and active member of the Concrete5 community, and I have used other plug-ins he has developed, so I knew it would be worth getting.