Having spent several hours reading about the features and limitations of services like DropBox and Jungle Disk and the hundreds of competitors they seem to have (as though everyone with an AWS account these days goes ahead and writes a file sharing application just for fun), I have yet to find one that would let a team of people at a small business collaborate without stepping all over each other's toes.

At a small business there are often many small documents per project — estimates, contracts, project plans, budgets — and team members frequently have to open and edit them, with all sorts of problems happening if two people edit a file at once. Even if a sharing service is smart enough to keep both versions of the file created, most small-business software (like word processors, spreadsheets, estimating software, or billing systems) has no way to compare — much less to merge! — the changes in two rival versions of a file that two people edited at the same time without each other's knowledge.

So, my question: are their cloud-based file sharing solutions that not only provide a virtual network drive that people can access, but that also let users lock files — even if it's not a real lock but just a flag or indicator — that could possibly prevent remote workers from both editing the same file at once?

Having one person wait for another person to finish editing is a very, very small inconvenience compared to the hour or more than it can take to compare two estimates by hand until you find and resolve the rival changes. Given this fact, I am surprised that almost none of the popular file sharing solutions seem to recognize this problem and provide some solution! Does anyone know of a service that does?