When using a CI server, like Jenkins, in conjunction with github, you may wish to use multiple deploy keys (github-speak for an rsa key pair that has been assigned to a single repo, rather than a user) to allow Jenkins to pull code from the github repositories

ssh-config-github-multiple-deploy-keys

# In the example here, where three repos are used, the idea is to take advantage of ssh's config mechanism
# For use with Jenkins, do the following:
# login to your CI Server
sudo su -s /bin/bash jenkins
cd ~/.ssh/

# then create three key key pairs
ssh-keygen -f id_rsa_project1
# on prompt, set target file to id_rsa_project1
# repeat for id_rsa_project2 and id_rsa_project3
# you should now have three key pairs: id_rsa_project1 id_rsa_project1.pub id_rsa_project2 id_rsa_project2.pub id_rsa_project3 id_rsa_project3.pub

# browse over to github and click on "admin" for each of the repo's, click on deploy key, and add deploy key
# copy over the .pub file contents for that repo's key pair
# repeat for all three repositories

# edit the ~/.ssh/config file
vim config
# enter contents like the following

Host project1.github.com
HostName github.com
User git
IdentityFile ~/.ssh/id_rsa_project1

Host project2.github.com
HostName github.com
User git
IdentityFile ~/.ssh/id_rsa_project2

Host project3.github.com
HostName github.com
User git
IdentityFile ~/.ssh/id_rsa_project3

# now go into your Jenkins control panel
# in your jobs, alter the configs (or create) so that
# anywhere a github reference is made
# substitute akin to the following:
# project1.github.com:MyOrganization/Repo1.git
#
# this works great because ssh will lookup project1.github.com in the config file
# and substitute in the hostname and user, and use the correct private key file
# that corresponds to the deploy key on the repo