Instashare [iOS, Free ($1 in-app upgrade to remove ads); Mac, Free] is billed as “AirDrop for iOS & OS X” and as far as I can see there’s no reason to dispute that claim. (Windows and Android versions are “coming soon.”) The app uses your local WiFi network or Bluetooth to transfer files; the in-app FAQ also describes how to create a personal access point if another access point isn’t available.

The Mac app [Free (in beta, no word on final price), website] is available from the menu bar, allowing you to drag files to any available device and access files that have been shared with you. The iOS app is almost as easy, with three screens (tabs on iPad): one for sharing files, another for sharing photos, and the last for settings.

Photo sharing from iOS to OS X is quick, much quicker than any other method I’ve used. Most recently I’ve been using Photo Stream to exchange photos: I open iPhoto and export or drag the image where I want it. But Instashare is much more lightweight; I no longer have to fire up iPhoto and only a tap and a drag sends a photo to my Mac.

The other way isn’t quite as easy; for some reason dragging directly from iPhoto causes Instashare to think it’s receiving a file much larger than it is and the operation times out. But you can use File > Reveal in Finder in iPhoto to expose the file, which you can then drag to Instashare.

Sharing between iOS devices is also quick and is perhaps the easiest way to share photos with someone close by. But I’m less sure of Instashare’s utility for sharing files between one’s own Mac and iOS devices. Instashare on iOS does allow you to view some file types, but most users will be opening the shared files in another app–so why not use Dropbox?

Although I did find one limitation–Instashare can only transfer one file at a time–a big plus for me is that the Mac app works on older Macs that are unable to use AirDrop. (However, only Lion and Mountain Lion are supported at the moment.)

Instashare is definitely something I’ll use in my workflow. Now if only someone would point me to an app that is as elegant in sharing clipboard contents between iOS devices.