http://www.webster.comis an amazing place! It's the Merriam Webster site. I've used it with 3rd grade up. It will pronounce words for the students to hear. It is both a dictionary & thesaurus & has bonus features like word of the day, word games. There is a section called the language zone that I found entertaining and educational.
http://www.visualthesaurus.com/desktop/index.jsp-An interactive site ivisual thesaurus. It has a 3D interactive interface that shows word relations, antonyms, synonyms, definitions, and the words used in context.
Publishing Opportunities for Students: Crunch http://nces.ed.gov/nceskids/crunch/ShowOff.asp- Are you a writer?A poet? Perhaps you're a top-notch muser. Whatever you are, how about sharing that creative genius on-line. Kids Online Magazinewww.kidsonlinemagazine.com- Click on the "Send Us Your Writing Link". Stone Soupwww.stonesoup.com- This magazine is for young writers and artists. Consider sending your work here. Word Dancewww.worddance.com- Word Dance is a quarterly non-profit creative writing and art publication that is 100% for and by kids (K-8th grade). The magazine contains no advertising and is professionally designed. Young Writerwww.mystworld.com/youngwriter- Young Writer (paper edition) is an international magazine featuring the best in English language creative writing from children aged 5 to 18 from around the world. Zuzuwww.zuzu.org - Click on the "Creative Writing" link to read student stories. Then try to submit your own.
http://www.superkidz.com/authors.html - Write to Authors. This teacher has had students write to authors for the past 8 years, and the authors almost always write or send us something back to the students!