Since switching to the Mac full-time last year, my only remaining complaint has been the abysmal (and finicky) FLAC support in iTunes. FLAC, or Free Lossless Audio Codec, is an open source lossless compression format that offers a nice compromise betweeen storing the uncompressed music file -- which is very large -- and converting the file to a lossy format like MP3 or AAC. Apple has its own lossless format, Apple Lossless, and Apple Lossless is great -- but I have lots and lots of live performances archived in FLAC and haven't wanted to spend the time converting all those files so that I can play everything in iTunes. About 6 months ago, I pretty much gave up and started just ripping CDs in Apple Lossless and using Max to convert favorite albums or performances.
Reader Mitchell wrote in and told us about Fluke, which aims to be an easier way to play FLAC files in iTunes. I've used other XiphQT based solutions, but none have worked as well as Fluke. Install Fluke and then open up a FLAC file with it (or drag your FLAC files to the icon) and it automatically runs a script that tricks iTunes into adding a FLAC file to the library. For the most part, tagging and even album art will be converted -- though I did have to add track numbers to some of the files I tested. It isn't as seamless as an actual FLAC player, like Cog, but it is certainly more hassle-free than some of the other script-based solutions I've used in the past.
Fluke is free and available for download here.