Wealth of Wikipedia

Poetry Main article about the art form, including history, rhythm, metre, rhyme, diction, forms and genres.
Introduction/Index Wikipedia’s own listing of many of its poetry pages.
Poets Many 100s of notable poets listed, with links to biographies.
Poems Many famous individual poems listed, with links to the work.
Poetic forms No fewer than 100 forms of poetry listed, each with a link to an individual article
History of Poetry Including sections on Western traditions, Chinese poetry, modern developments and lyric poetry.
Metre Including sections on quantitative v. qualitative metre, feet, half-lines, caesura, variations in different languages and dissent.
Rhyme Types of rhyme: perfect, general, mirror (eye, mind), classification by position, history, in various languages, function.
Alliterative verse Alliteration as principle structure as opposed to rhyme or syllables, etc. Especially in German and Norse poetry.
Assonance Numerous examples of assonance.
Visual poetry Poets listed and links to pages on various types, i.e. calligram, concrete, digital, etc.
Rhyming schemes Schemes from alternate (abab, cdcd) and the ballade to the villanelle – each leading to its own full page on Wikipedia.
Poetic diction In Greece and Rome, Germanic, Japanese, in English – with Wordsworth quote, as preferring “the very language of men”.
Lyric poetry Essentially a history of largely personal poetry. Many references cited and links provided.
Narrative poetry A brief introduction and a listed links to many outstanding examples.
Schools, movements or groups Listed, with some brief descriptions, and links to many articles from Absurdism to Uranian.