QueryBuilder can be used on advanced search engine pages, administration backends, etc. to build complex queries or filters. It is highly customisable and can be used with many jQuery widgets like autocompleters and sliders.
It outputs a structured JSON of rules which can be easily parsed to create SQL/NoSQL/whatever queries.
SyncToy 2.1 is a free application that synchronizes files and folders between locations. Typical uses include sharing files, such as photos, with other computers and creating backup copies of files and folders.