Dropbox is perfect, but as a company, no one can host anything worthwhile on servers that we don't control.

So I've been tasked with coming up with a Dropbox alternative, something in house.

GlusterFS is nice, but no offline access. SparkleShare uses Git which isn't great for large files. It also doesn't have windows ports.

Any other options?

If I were to roll out my own from scratch, what do you think the based way to go about doing this would be?