The Mac version of Amazon’s Send to Kindle is now available (via Jacqui Cheng). There’s a (cross-platformish looking) app that supports drag and drop, a printer driver, and a contextual menu plug-in. You can choose which Kindle (or iOS device with the Kindle app) to use as the destination and also archive the files in Amazon’s cloud. Of course, you can still send files via e-mail. Meanwhile, Apple’s iBooks supports fewer file formats and can only receive files via iTunes.