Toolsley PGPigeon

PGPigeon is a simple but powerful OpenPGP-compatible message encryption webapp based on the openpgp.js library. You can encrypt, decrypt, sign and verify signatures (of plaintext messages as well as encrypted ones). The encrypted message can be sent over email or any other channel. Fetching keys from key servers is also supported. PGPigeon is currently in BETA. Please report any bugs you may encounter.

Screenshots from Chrome Web Store