I’ve mentioned VoltaicHD in the past as a way to process AVCHD footage without going through iMovie’s or Final Cut’s import process; those programs convert the footage to AIC (Apple Intermediate Codec) for editing. VoltaicHD allows you to copy the .mts files directly to your hard disk and perform the conversion on your own time. As a bonus, it brings AVCHD support to PowerPC-based Macs, since Apple’s solutions require Intel-based machines. (See Import AVCHD Later with Voltaic.)
Justin at Shedworx wrote to me about a nifty utility they’ve concocted: HD Quick Look, a plug-in for Mac OS X Leopard that displays the first frame of an .mts file to give you a better idea of the clip’s contents before converting it.