Best way to crack LM hashes ?

According to your experience, what is the best (fastest) way to recover a LM hash ?
Bruteforce ? Huge dictionnary ? Other ?

Thank you for your help.
if you have the power, brute force. if not, rainbow tables. lm is about the only application where rainbow tables are still relevant, provided you do not have sufficient compute power. of course dictionary attack can also be quite beneficial as well.
I have a HD 7970, but the full charset bruteforce is still long.
I can't find GPU rainbow tables for LM ! Do you have a link ?
yeah, brute force would take a bit of time with only a single gpu.

frt should have them, but they might be cuda only. bitweasil might be willing to generate some for grtcrack. would only take a few minutes to gen on our cluster.