phonics
Reading Eggs
A subscription-based sight which guides your child through fun reading lessons, only letting them advance to a new level when they've mastered the earlier concepts.. Primarily takes a "whole language" approach to teaching reading, but includes some phonics instruction too. The site is based in Australia, and uses Australian English rather than US English, but it's barely noticeable.
Gamequarium
A site with a large variety of educational games for elementary students. Use the search box on the site to find the kind of game you're interested in.
GameGoo
Language arts games, beginning with letter recognition, and covering more advanced concepts like poetry, synonyms & antonyms, and spelling.
Between the Lions
Games, stories, and video and audio clips from the PBS tv show that teach phonics and other skills for the beginning reader.
Ed Helper
Math, Reading Comphrension, Design/Create Puzzles, Math, Kindergarten-3rd Grade, arts
I Know That
Educational Games for kids in preschool, kindergarten and elementary school ages.
BBC: The Little Animals Activity Centre
Reading, word games, make something activity center, music/videos, puzzles, and number games.