The Signal ID Wiki (sigidwiki) is our sister site that we started a few years ago as a way to collect and catalog various types of signals that an SDR user might see and hear on the airwaves. The idea is that a user could search the database to learn about and identify unknown signals. Over time it has grown significantly, with now almost 400 known signals with both waterfall images and sound samples available in the database. Special thanks to lead admin Carl Colena for maintaining and playing a huge role in the databases' growth.
Artemis is an open source Windows/Linux/MacOS compatible application initially programmed by Marco Dalla Tiezza. It brings the sigidwiki website into an offline searchable database with an easy to use UI. Today version 3.0 was released to the public. The new version has been completely rewritten from scratch in Python, as the previous versions were written in BASIC (a now abandoned programming language). The new version has an improved UI, and paves the path for future improvements.
Marco notes that in the future they hope to add an Autocorrelation function, which might help users automatically identify certain types of repetitive signals simply by playing the raw audio into Artemis.
Note that in order to download the software you will need to sign up to their forum, which is free.