Shadow Poetry: An excellent site with all sorts of information about poetry -- It's my favorite site for poetry!
Elements of Poetry: Explanation of poetry, imagery, language, tone, rhythm, meter.
Poetry Terminology: Terminology of poetry.
Shadow Poetry: Poetry forms and examples.
Elfwood: Poetic forms with examples.
Baymoon: Poetic terms and forms.
Poets' Graves: Glossary of poetic forms
Richmond Education: List of important literary terms.
Poetry Magic Resource center for theory and craft of writing poems - includes publishing.
Cummings Study Guide: Meter in poetry and verse.
Tripod: Rhyme form, theme, meter, imagery, persona.
Dictionary.com: Dictionary, thesaurus, encyclopedia, translator.
Rhymezone: A site to find rhymes, synonyms, and definitions of words. A very useful site.
Sol Magazine: Poetry forms and examples.
The Workshop: Poetry forms and terminology, descriptions and example.
Wordscount: Counts the syllables of a word.