I would like to generate a large number of public Bitcoin addresses (several hundred thousand) quickly and efficiently into a simple text file. What would be the easiest way to get this done? I'm just wondering if there are any particular scripts or services that handle this already without having to roll my own.
If you want to generate a lot of keys in the wallet.dat, use command line parameter:
-keypool=<n> Set key pool size to <n> (default: 100)
Then you can extract the results with Pywallet.
If you want to make them separate, you will have to use a cryptography library that supports secp256k1 ECDSA, like the Bouncy Castle. Simply generate private keys, use the library to generate public keys from them, and then convert them to classic Bitcoin address using this algorithm (requires libraries that support SHA256 and RIPEMD-160).