Dave Sperling's ESL CAFE provides practice of phrasal verbs. Simple Sentences deals with the parts of a simple sentence and how to put them together. The Collective Noun Page provides an alphabetical listing of collective nouns. Countable and Non-Countable Nouns provides explanations and rules for this area of grammar. Verb Tenses gives explanations and rules on verb tenses.
Spelling offers hints and interactive quizzes for spelling.
Susan Jones' Spelling Rules provides a complete list of spelling rules for nouns and verbs. The Grammar Clinic is Edunet's grammar help page.