(Other outside links bearing on particular topics are now found scattered
throughout the website)
The Biblioteca Digital Dioscorides and the Biblotheca Antiqua of Aboca Museum include many botanical texts on which Cowley's own builds. The first edition of John Evelyn's Sylva, in which Cowley's Plantarum quite clearly played a generative role, if we judge from Evelyn's tributes to Cowley in later editions, is online at the British Trees website; there are also web-pages devoted to Evelyn's remarkable archive (British Library) and selections from his Diary and other works.
For a rich online verse corpus hailing the Stuart Restoration see Gerald MacLean's The Return of the King, and for Cowley's contemporaries Milton and Marvell see http://www.richmond.edu/~creamer/milton/, http://www.luminarium.org/sevenlit/marvell/marvbib.htm and http://www.library.utoronto.ca/utel/rp/authors/marvell.html.
Cowley's Works on the Web // Sprat's life of Cowley (English version) // Samuel Johnson's life of Cowley // additional Luminarium links, with a gathering of Cowley's lyrics set to music by noted composers from Purcell to Schubert at http://www.recmusic.org/lieder/get_author_texts.html?PoetId=601.
Dana F. Sutton's online editions of Cowley's Latin writings are available at Philological Museum. (Also see her immense catalogue, Neo-Latin Online--major texts by Erasmus and others--supplemented by texts and brief bio-bibliographies at the useful Scholasticon website).
And the Chadwick-Healey English poetry subscription database includes all Cowley's verses in English, while two other subscription databases, Early English Books Online and Eighteenth Century Collections Online, comprise most early Cowley editions in digitized form.