My personal collection of derivations, currently ranging from packaging small niche projects to prereleases of popular ones though more might be added in the future.
Available via the Nix User Repository with pkgs.nur.repos.syberant.package-you-want-to-install.
Note that the NUR is not checked for malicious content so you should carefully check the software you're installing.
See the documentation there for more details on how to use the NUR.