I've been working on an installer for a Windows service using Nullsoft Scriptable Install System. This installer creates a special account to run the service under, but to do so, it has to come up with a random password. NSIS offers a few existing mechanisms for random numbers, but neither are anything but basic PRNGs.
In order to get *good* random passwords, we want the equivalent of /dev/urandom. Microsoft provides the CryptoAPI, which includes the CryptGenRandom() API. I developed a DLL plugin for NSIS called Pwgen that collects entropy from the OS and generates a random password, restricted to the 62-character set of alphanumerics.