Curve25519 is described in Curve25519 for ephemeral key exchange in Transport Layer Security (TLS) IETF draft. It's designed with speed, simplicity and security in mind, and seems to be very nice alternative to NIST curves like secp256r1 or secp384r1 - especially when we think about rigidity and susceptibility to secret attacks.

It would be very nice to have it supported in OpenSSL to speed up adoption of ECDHE key exchange (kEECDH), especially among those people who don't trust curves coming from NIST.