Clearly there are many ways to transfer files from one computer to another, so just as clearly, JustBeamIt is meant to be a convenient alternative that may be worth checking out.
It certainly is a viable quick option relying on the likelihood the machines are all connected to the Net, maybe even on the same WiFi. It does look like it’s primarily designed for dirt-easy transfers between machines in close proximity to each other, like in your home office, and you just don’t want to go hassling with a flash drive.
Using it is indeed simple: Just visit the site, drag the file onto it, and click on Create Link. It’ll give you a unique link to share with the other machine practically instantly, no twiddling your thumbs waiting for it to upload.
And here’s why: JustBeamIt doesn’t start uploading until the other side accesses the link to download the file. This means, best keep your browser open until the other machine has the file.
The link itself is temporary—it’s just single use with a short 10-minute life, and nothing’s really stored online, which is why it isn’t really ideal for transfers between remote machines. For local machines, though, JustBeamIt is a pretty darned nifty option.