Sorry, I'm a bit of a newbie to SFDC development but was wondering if someone has a solution that I can use to roll-up data from a related list without a master-detail relationship between the two objects. I can't seem to find the answer on any existing discussion threads although there are a few people trying to similar things. 

The situation:

I have a related list of Contracts (standard object) on a custom object, Instruments. These Contracts have an End Date which I would like to roll-up to the associated Intrument record. Essenially I would like to show the MAX(Contract.End_Date) on the Instrument record for all Contracts assosciated with that Instrument. 

Obviously a Roll-up Summary Field won't work here because of the lack of a master-detail relationship, so I was thinking an APEX Trigger is the only option. Does any one have suggestions on how this can be accomplished? Do I need to go the APEX Trigger Route or is there an easier option? And if I have to use an APEX trigger, do you have any code examples I can reuse?

Thanks for your help!
Cam