Pi-hole is a Linux network-level advertisement and internet tracker blocking application which acts as a DNS sinkhole, intended for use on a private network.
Mylar is an automated Comic Book (cbr/cbz) downloader program heavily-based on the Headphones template and logic (which is also based on Sick-Beard).
NZBHydra is a meta search for NZB indexers. It provides easy access to a number of raw and newznab based indexers. You can search all your indexers from one place and use it as an indexer source for tools like Sonarr, Radarr or CouchPotato.
SABnzbd is a multi-platform binary newsgroup downloader. The program works in the background and simplifies the downloading verifying and extracting of files from Usenet.