The short/long inputs as well as their correct hashes are supplied by the FIPS 180-2 specification; it can be found at http://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf. The short/medium/large inputs for HMAC and their corresponding correct hashes (at least for SHA-1) can be found at http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf.
Instructions: By default, this page should load 10 of the 15 test vectors given by the FIPS 180-2 specification and 3 of the 4 test vectors given by the FIPS 198a specification. You may also change any of the input values and then click off the input box to have the hash update.