Here’s a selection of guitar software I’ve added to Shareware Music Machine in recent weeks. As always, downloads are available for all software listed.

GNUitar 0.3.2 is an Open Source real-time guitar processor. Effects include reverb, delay, wah-wah and more. It’s free so give it a shot.
Full details and download:
Windows
Linux

Guitar Shed is a set of tools for guitarists, bassists, and other musicians. It includes a guitar tuner, metronome, tablature organizer, tab finder, chord library, jam machine, song jammer, gig manager, web manager, and much more.
Full details and download:
v2.0 for Windows
v2.9 for Macintosh OS X

Cortex 0.8 is a free VST guitar amp.
Full details and download:
Windows

G-amp is also another virtual amplifier. Also Freeware and available in Phat and Lite versions for Windows.
Full details and download:
Phat
Lite

Guitar Guru shows you how to play your favorite guitar songs on your PC, synced to your CDs.
Full details and download:
Windows

Guitar Leads and Riffs Play Along tuition software lets you to read the tabs, hear the audio of the lead and then play along.
Full details and download:
Windows

Guitar Mentor v2.0 is guitar instruction and scale/tonality calculation software.
Full details and download:
Windows

Download more:
Guitar Software
Software for Bass players
Tablature Software
Tuning Software
Specialized Chord Software