EMV Lab - a number of tools for working with ASN.1 encoded messages, CAP data, simple cryptographic functions.

Cryptographic Keylength Recommendations - "the web-site summarizes reports from well-known organizations allowing you to quickly evaluate the minimum security requirements for your system".

Random number generator - one can get a string of hex number by selecting 1 column, range 0-255 and output format as hexadecimal.

Large number calculator - e.g., for hand verification of RSA signatures.