COPTR is a wiki based registry of digital preservation tools. It's main aim is to help practitioners discover preservation tools that will help them tackle particular preservation challenges. It can be browsed and searched directly by practitioners, or queried by other systems via an API.
Each tool in COPTR is categorised by the Lifecycle Stage it falls within, the (sub) Function it performs and by the Content Type that it operates on. For example, EpubCheck performs the Function Validation and operates on EBook Content. COPTR can help by enabling you to browse to tools that meet a particular need - perhaps relating to a specific Content Type or Function.
COPTR also holds digital preservation workflows.
Check out this wish list of tools to add to COPTR.