HTCFlasher (formerly known as HERMflasher) is a tool which allows you to flash ROMs on most current HTC devices. It has some extra features that the original HTC RUU doesn't have. For example, it can present a serial prompt to the bootloader (replacing mtty), or it can dump NBH file contents (.nb ROM parts).
eINIT is an alternative init system. It's quite fast, since it can potentially be used without the help of any scripting at all, but it is still flexible and extremely modular. The focus is on speed and parallelisation, mostly with embedded devices and low-downtime servers in mind, and benchmarks do suggest that it's doing a fairly good job at that. It compiles cleanly (and should thus work, provided someone writes appropriate modules) on Linux, FreeBSD, and Darwin/Mac OS X.