Today I needed to install MongoDB on one of my servers, however it still runs on 8.04 LTS, and MongoDB don't provide a dedicated apt package for that release. However you can safely use the 9.04 Jaunty source lines. It will at least save you compiling from source and maintaining it yourself.
Edit your sources.list...
sudo nano /etc/apt/sources.list
Add this to the bottom...
deb http://downloads.mongodb.org/distros/ubuntu 9.4 10gen
Then run these commands...
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv 7F0CEB10
sudo apt-get update
Finally install MongoDB...
sudo apt-get install mongodb-stable
Job done!
