Ranked in these QuestionsQuestion Ranking
Pro Has packages for popular distributions
ScudCloud has packages for Ubuntu, Kubuntu, Mint, Debian, Arch, Fedora and OpenSUSE.
Pro Free and open source
It's free and open source, released under the MIT License.
Pro Native notifications
Pro Channel quicklist for Unity
Ubuntu Unity's dock menu (accessed via right-click on icon) allows quickly switching to the needed channel.
Pro Icon badges
Count of undread notifications will be overlayed over the launcher icon.
Installation alone was less than 1MB.