XtraMath - Helps master basic math facts.
Kindergarten/1st Grade Math - Lots of activity ideas, crafts, and printouts. (123 Homeschool 4 Me)
Addition Facts 1-10 - Videos that teach all the ways to add to numbers from 1-10. (PK1 Homeschool Fun)
Math 1 - Full curriculum. Learn addition facts from 1-5. (Easy Peasy)
Math 2 - Full curriculum. Learn addition facts from 6-9. (Easy Peasy)
Addition Worksheets - Add with dice, color by number, and flash cards. (K12 Math Worksheets)