Anyone knows a good summary containing the most important definitions and theorems about functional analysis.
Georgei E. Shilov's Elementary Functional Analysis, 2nd Ed. (Dover books, 1996) would be a great start, and cheap, as far as textbooks go!
For a very brief (17 page) "summary" pdf document, written and posted by Dileep Menon and which might be of interest: An introduction to functional analysis. It contains both definitions and theorems, as well as a list of references.