SmartHomeUSA.com Home Automation

[Simpleton]

Hi,
I am not sure where to post this so I'll ask here. Basically, I need advice on what to get in my situation. I live on a college campus so I am unable to change the visible appearance of the lock. Also, I have to keep the current lock in place but I would be able to change any parts that aren't visible with the door closed. So basically my question is, are there any keyless entry systems that I could use in this case so I don't have to carry 3 keys around with me to just get into my room and would only have to carry 1 to get in the main building instead? I know this may seem like a waste of time and money but I'm so used to the RFID + keypad entry system I use while at home that the keys are now such an inconvenience. I am open to using pretty much any type of system, whether it be RFID or some other system that is secure enough to be used in this situation (living on campus with hundreds of people I don't trust enough to not try and get in). Please let me know if anything comes to mind as it would be a lot simpler to find an already made solution rather than having to build some overly complicated solution myself.
Thanks,
Ray

[Simpleton]

Sorry to double post, but just as an example, the plan I had in mind at this moment was to borrow some ideas from Here. I was thinking of getting a voip account and have it restricted to only allowing calls from my cell phone and have it so when I called the voip number, I could quickly enter a PIN and once it verified it, have it open the door through a retrofitted mechanism that would push down on the lever handle that is on the doors. As you can see this is definitely a complicated idea and would require me to write a complex program as well. If there is anything somewhat similar to this that is already premade that would definitely be something I am interested. If not, any ideas are appreciated.
Thanks,
Ray