I had a look at ReaderwareAW, the audio CD cataloguer.

Pros:
- Cross-platform (Mac, Win, Linux) compatibility.
- Drag-and-drop data entry from web site.
- Solid database core; it includes track artist and composer fields.
- Extensive search capability.
- Server/client option (valuable for home network).

Cons:
- Java -- it "feels wrong"; some interface elements behave in unexpected ways; sometimes it's sluggish.
- No automatic entry of mounted CDs (no support for freedb, CDDB, iTunes, CD Info.cidb).
- No support for accessing sites other than the usual English-only ones (Amazon, etc.).
- Data import limited to CSV and tab-separated; no import/export of track data (track titles, composers, etc.)
- Detail view not customisable.
- No scripting for database management tasks.

The main alternatives are CDpedia, Delicious Library, and Music Collector (iCDc and InCDius GH may also be considered). I haven't tested Music Collector because it requires an installer (which, unlike Readerware's, doesn't provide a list of what will be installed and where). ReaderwareAW is superior to Delicious Library in everything except user interface; it has a better database structure than CDpedia, but it lacks support for freedb/CDDB, and has fewer import/export capabilities.

There are three points which prevent me from choosing ReaderwareAW: (1) interface (least important, can be got over in time); (2) lack of support for mounted CDs and freedb/CDDB; (3) lack of support for importing track tags -- title, artist, composer -- from text files (most important).