Fun Brain Grammar:
http://www.funbrain.com/grammar
Check out this website for fun grammar games.
Grammar Blast:
http://www.eduplace.com/kids/hme/k_5/quizzes/index.html#five
This is a MUST visit website. Practice verbs, nouns, adjectives, adverbs, prepositions, pronouns, capitalization, and punctuation.
Phonics:
http://www.sadlier-oxford.com/phonics/student.cfm
Scroll down for grade 3 and 4 activities but, feel free to explore and practice other skills on the site. The activities are fun and cover some of your favorite skills such as synonyms, antonyms, homonyms, suffixes, prefixes, digraphs, dictionary and sentences.