Prebuilt packages are available for Debian/Ubuntu and Arch, and via Docker Hub.
Debian/Ubuntu
A package repository is available at https://repo.jellyfin.org.
For instructions on using the repo, please see the Jellyfin Debian Repository page. Direct .deb downloads, including old versions, are available at https://repo.jellyfin.org/archive.
NOTE: Ubuntu users may find that the ffmpeg dependency package is not present in their release or is simply a rebranded libav which is not directly compatible. Please obtain the ffmpeg package directly from the FFMPEG site to use Jellyfin on Ubuntu.
Docker 
The Jellyfin Docker image is available on Docker Hub.
Arch
The Jellyfin package is in the AUR at https://aur.archlinux.org/packages/jellyfin-git/.
Unraid
An Unraid Docker template is available. See this documentation page for details on installing it.
Windows
Windows builds courtesy of @LogicalPhallacy are available at https://repo.jellyfin.org/windows.