Which Two-factor authentication methods are available at which exchanges? I see that Mt. Gox now supports the Google Authenticator app (on Android, iOS - iPhone, iPad, iPod Touch, and on Blackberry) for 2-factor authentication (in addition to support for Yubikey, of course).

What are all the various 2-factor (also referred to as multi-factor) methods available for Bitcoin-related sites (exchanges, eWallets, mining pools, other services, etc.)?
Bitcoin Currency Exchanges:


Mt. Gox: OTP using YubiKey or Google Authenticator

Options: [On Login] | [For WIthdrawals] | [For Changes To Security]

Camp BX: OTP/Google Authenticator
Bitstamp: OTP/Google Authenticator
Bitcoin-24: OTP using Google Authenticator and for withdrawal SMS messaging
Bitcoin-otc: GPG authentication with gribble bot
BitMarket.eu: OTP/Google Authenticator
Coinbase - OTP/Authy or OTP/Google Authenticator
FYB-SG (Singapore) - OTP/Google Authenticator
VirWoX - OTP/Google Authenticator
WeExchange.co - OTP/Google Authenticator
BTC-E - OTP/Google Authenticator
Local Bitcoins - OTP/Google Authenticator
bitcoin.de - OTP/Google Authenticator or Yubikey (but not Mt. Gox Yubikey)


Other Exchanges:


MPEx: GPG authentication
ICBit.se: OTP/Google Authenticator
BTC Trading Corp (BTC-TC): OTP/Google Authenticator or YubiKey
BitFunder: OTP/Google Authenticator


Other Services:


BitPay: OTP/Google Authenticator


EWallets:


Blockchain.info/wallet - Google Authenticator, e-mail verification, SMS, and YubiKey (but not Mt. Gox YubiKey).
WalletBit - SecureCard (or perhaps OTP/Google Auth has been added now?)
Coinbase - SMS text messaging-based two-factor, Authy (Android/iOS app similar to Google's)
Paytunia - OTP/Google Authenticator or Yubikey (but not Mt. Gox Yubikey)
bitZino - OTP/Google Authenticator
Just-Dice - OTP/Google Authenticator


Mining Pools:


MaxBTC - Yubikey and Google Authenticator
EclipseMC - Supports Yubi/GA OTP