Dr. Sheldon Cooper has already covered quite a bit of ground on this topic
http://bigbangtheory.wikia.com/wiki/The_Roommate_AgreementSkynet Clause: Leonard will help Sheldon destroy an Artificial Intelligence that Sheldon has created that is taking over the earth. ("S2 Ep6")
◾ Body Snatchers Clause: Leonard will help Sheldon destroy someone who they know that has been replaced by an alien pod.("S2 Ep6")
◾ Godzilla Clause: Presumably, Leonard will help Sheldon destroy a monster that has destroyed Tokyo. ("S2 Ep6")
◾ Section C: Sheldon can call for an emergency meeting. ("S2 Ep10")
◾ Unnamed Clause: Leonard will name Sheldon as his sidekick if Leonard obtains superpowers. ("S2 Ep10")
◾ Section 9: The apartment's flag is a gold lion rampant on a field of azure and should never be flown upside down, unless the apartment is in distress. ("S3 Ep22")
◾ Section 9: If one of the roommates ever invents Time Travel, the first stop has to aim exactly five seconds after this clause of the Roommate Agreement was signed. ("S3p22")
◾ Section 74C: Leonard must assist Sheldon if he ever becomes a robot ("S4 Ep2")
◾ Unnamed Clause: If Sheldon turns into a Zombie, Leonard cannot kill him.
◾ [Clause] : If one of them will be visiting CERN, they must take the other roommate along. ("S3 Ep15")
◾ Friendship Clause: Sheldon will take Leonard swimming to Bill Gates' house should he ever be invited. ("S3 Ep15")
◾ Unnamed Clause: The thermostat must be kept at 72 degrees at all times. ("S3 Ep22")
◾ Unnamed Clause: Fridays are reserved for watching Firefly due to Sheldon's assumption that it would be on for years. ("S3 Ep15")
◾ Unnamed Clause: Leonard must drive Sheldon to work. ("S3 Ep15")
◾ Section 37B: Miscellaneous Duties: Leonard is obligated to drive Sheldon to his various appointments, such as to the dentist. Leonard must also provide a "confirmation sniff" to tell if questionable dairy products are edible. ("S5 Ep15")
◾ Addendum J: When Sheldon showers second, any and all measures shall be taken to ensure an adequate supply of hot water. ("S4 Ep21")
◾ Unnamed Clause: Thursday night is Jets pizza night. ("S4 Ep21")
◾ Unnamed Clause: Selection of a new takeout restaurant requires a public hearing and a 60-day comment period. ("S4 Ep21")