Musical Instruments in the Yahoo! Directory

Harmony Central
Resource for musicians includes guitar, bass, synths, MIDI, software, effects and more.
www.harmony-central.com
Sonic State
Built by musicians for musicians, includes reviews and articles on synths, drum machines, effects, MIDI, software. Includes directories, classifieds, chat rooms and more.
www.sonicstate.com
Oddmusic.com [read review]
A source for anyone interested in unique, unusual, ethnic, or experimental music and instruments.
www.oddmusic.com
Musical Instrument Makers Forum
Online discussions and interactive courses about acoustic and electric guitar building, and information on lutherie, woodwind and brass instrument building and repair.
www.mimf.com
Music Gear Review
News and reviews covering guitar, bass, drums, keyboards, software, effects, amplifiers, accessories, and more.
www.musicgearreview.com
CHICO Instrument Encyclopedia
Search for the musical instrument of your choice or browse through the collection by the Sachs-Hornbostel classification scheme or by geographical origin.
www.si.umich.edu/chico/instrument
Gearwire
Offers videos, news, and reviews of guitars, bass guitars, keyboards, amplifiers, recording equipment, and more.
www.gearwire.com
Unusual Instruments' Music Videos
Blogging about such oddball musical instruments as the glass harmonica, the Stylophone, and the aeolian harp.
weirdinstruments.blogspot.com