Typing

Dance Mat Typing (Ages 7-11)
TypingWeb
FreeTypingGame.net
TypeRacer (Advanced)

Complete Curriculum Options

Preschool
Brightly Beaming Resources (PreK-Early Elementary)
First School Preschool (thematic units, Pre-K-K)
Read to Me and ABC (PreK) **Added 7/24/13

Charlotte Mason
Ambleside Online (K-12)
Mater Amabilis (Catholic, K-8)
Higher Up and Further In (AO-inspired, K-12)
Tanglewood School (1-8)
Simply Charlotte Mason Curriculum Guide (K-12)
Milestones Academy (K-10)

Classical
The Classical Curriculum (PreK-12)
Classical Homeschooling (K-12)

Primarily Public Domain Text-based
An Old-Fashioned Education (K-12)
Your Free Homeschool Library (K-12) - While I do not provide a schedule or specific book recommendations, I have gathered a plethora of vintage textbooks and categorized them by grade and subject, making it simple for a teaching parent to choose what they need to teach most of the core subjects.

Primarily Web-Based
Lesson Pathways (K-5)
Easy Peasy All-in-One Homeschool (K-High School)
EZSchool (K-12)
DiscoveryK12 (K-12) *Added 9/6/16*
HippoCampus (covers math, science, social studies, and religion, Middle-High School)
Connexions (High School-Adult)

Flashcard/Worksheet-Based
Free World U (K-12)
Head of the Class (K-5) *Update 7/5/13* This site appears to be closed, but I will leave here in case it returns.

Core Knoweldge-Based
Baltimore Curriculum Project Core Knowledge Lessons (K-5)

Single Year Unit Study
Teaching with God's Heart for the World (Elementary)

School Curriculum Guide
Hillsdale Academy Curriculum  (requires free registration, K-12)
Liberty Academy Online Curriculum Guides (scope and sequence, 3-12)

Reformed
Puritan's Home School Curriculum (K-12)

Music

Music Tech Teacher (Elementary)

Logic and Critical Thinking

Critical Voter Curriculum Upper Middle-High School+
Microsoft Critical Thinking Curriculum Middle-High School
A Formal Logic Primer Upper Middle-High School+

Latin and Greek

Latin and Greek
Textkit (Greek and Latin grammars, readers, and answer keys)

Latin
National Archives Beginner's Latin (not classical Latin)
Study Guide to Wheelock's Latin
Latinum
Wikibooks Latin
University of Texas at Austin Linguistics Research Center Latin Online
Latin for Mountain Men
Allen and Greenough's New Latin Grammar for Schools and Colleges
Fr. Gary Coulter Latin (Catholic)
Latin Handouts
The Latin Library

Fun Stuff
Headventureland (website of Classical Academic Press, has some Greek and Latin videos and games)
Greek Word of the Month
Latin Word of the Month

Modern Foreign Language

Spanish
123TeachMe.com  (Elementary to Adult)
OnlineFreeSpanish.com (Elementary)
Salsa (Elementary)
Duolingo (Middle Grades to Adult)

P.E. and Health Curriculum

Physical Education
Operation Fit Kids Curriculum (3-8)

Religious Education

Bible
Bible Road Trip: A 3-Year Bible Survey

Information and Communication Technology

Digital Literacy and Citizenship
CommonSense Media Curriculum

21st Century Literacies
21st Century Literacies

Art

Various Media and Techniques
KinderArt
Teach Art at Home Free Lessons
See the Light Free Lessons
Making Art Fun
Art Projects for Kids
Art Smarts 4 Kids
Learn to Draw and Paint
WeeFolkArt (ages 4-6)

Drawing
Drawspace
Donna Young Drawing Lessons

Painting
Bob Davies Watercolor Tutorials

Artist Study
The World's Greatest Artists Volume 1