To make things easier for Ubuntu users to use I2P-based applications, I run the Unofficial I2P PPA. Ubuntu Precise, Quantal, Raring, and Saucy are all supported. The PPA will be kept in sync with my Debian repository.
Ubuntu
Ubuntu users can add the PPA at a console prompt with:
sudo apt-add-repository ppa:i2p.packages/i2p
Debian
Debian isn't supported by the PPA system but many packages can still be installed from this PPA. A better option would be to use the Debian package repository.