AndroidZoom, along with just about every other third-party interface to the Android Market out there, provides 2D barcodes which aim to make it easy to install Android applications that you find online on a phone. Maybe this would be a nice feature for F-Droid?

Unfortunately, I found this feature when I was trying to help a friend install the (free software) ZXing Barcode Scanner because they wanted to read a 2D barcode.