My personal record is over 12 years.
I applied for some temp work, doing building work (among other things). At the time I was at university, so wanted to make money in my time off. I never heard back from that particular agency, and wrote it off as a bust.
Cut to a decade after finishing uni. I get a random call, to see if I am available. I'm now a veteran freelancer, in a highly specialist field, so I'm used to being cold called with work offers. It quickly becomes apparent that they are not talking about my field however.
I eventually got enough info out of them to realise where the info must have come from. Even funnier was how annoyed she was that I hadn't made them aware I was no longer available! I don't know which is more impressive/disturbing, that they kept my application for that long, or that they were so short handed that they managed to get that deep into the pile of old applications!