Deterministic key generation
What you want is a key derivation function (KDF).  Here's a fairly thorough list of some standardized ones.

Ps. The suggestion given by user1852723 to use HMAC, with your "seed" as the key and a counter (or other non-repeating sequence) as the input, more or less corresponds to the "Counter mode KDF" construction described in NIST SP 800-108, with HMAC as the underlying PRF.