iTunes Backup and Restore Rating Scripts 0.1 (by Heiko Kretschmer)
Since iTunes Library keeps crashing occasionally I was searching for a way to preserve all metadata.

HiRate 1.0 (by Michael Aquilina Software)
Hidden functionality is built into iTunes that allows songs to be rated on a scale of 0 to 100 instead of just 0 to 5.

Rating Writer 1.0 (by Thunder & Lightning, Inc.)
Rating Writer is a small utility for iTunes 4 and Mac OS X that allows the user to write their current song ratings to the song's ID3 tag (in the comments field) and then later restore the ratings to a different iTunes library.

Rate Current Song Scripts 1.6 (by Walker Publishing Unlimited)
This set of scripts was written to help rate songs on headless Macs running iTunes.

iTunes Star Changer 1.0 (by Romeo Opena)
iTunes Star Changer is a small AppleScript that allows quick rating of song tracks, in single-track mode or in batched track mode.

RatingList 1.1 (by Darkworks Software)
RatingList is a REALbasic control which provides a listbox that supports a rating column like the one in iTunes.

Star 1.3.1 (by Improv, Pastence)
Does you iTunes library lack Stars? Does it whine at not having enough shine?

If you answered yes to either of those question, then you need Star! the wonder app.

FastTunes 1.2.3 (by Toon Van Acker)
FastTunes is a utility that helps you control iTunes.

WBC iTunes Scripts Collection 1.8 (by Wooden Brain Concepts)
These are a number of scripts that work with iTunes, in conjunction with other programs.

Album Art Widget 2.8 (by liquidx.net)
Album Art Widget - A fast and compact album art and song rating displaying widget.

SlimServer 6.5.0 (by Slim Devices, Inc.)
Slim Devices introduces SlimServer 6.

NoteAbilityPro 2.319 (by Keith Hamel)
NoteAbility Pro is a professional music notation package for the Macintosh OS-X operating system.

netTunes 2.3.1 (by Shirt Pocket)
netTunes lets you control iTunes running on one Macintosh from another, using iTunes' native interface.

v.m.k 1.6 (by Fredrik Olofsson Musikproduktion)
This application lets you simulate a midi keyboard on your computer keyboard.

Audio Hijack 2.2.5 (by Rogue Amoeba)
Audio Hijack gives all your audio that extra bit of sweetness.