The Meno is among the most famous of Plato's shorter dialogues, thanks to Socrates exposition of the theory of innate knowledge or anamnesis, by using close questioning to elicit from a slave geometrical knowledge that he did not know he had. The problem to which this theory is a response, of how we can come to know anything of which we are originally ignorant, has become known as Meno's paradox.
Free Online and Downloadable Texts
Gutenberg: Meno by Plato, translated by Benjamin Jowett, multiple formats.
Loebulus. L165 - Plato - Laches. Protagoras. Meno. Euthydemus. PDF of public domain Loeb edition in Greek and English.
Social Science Research Network: Meno, translated by Cathal Woods (2012).
University of Adelaide (Internet Archive): Meno, translated by Benjamin Jowett. EPUB, HTML and MOBI formats.
Approaching Plato: A Guide to the Early and Middle Dialogues
Dale E. Burrington: Guides to the Socratic Dialogues.
History of Philosophy without any gaps: We Don't Need No Education: Plato's Meno - podcast by philosopher Peter Adamson.
PhilPapers: Plato - Meno - bibliography with open access option.
The Great Conversation: Further reading at Tom's Learning Notes
Ancient Greek resources: Learn to read Greek classics in the original.
Bloom's Western Canon: Plato's Dialogues are listed.