Teragon Audio has released BeatCounter, a plug-in designed to facilitate beat-matching from within a VST-host. It determines the beats per minute (BPM) of its input source, and displays both the current and accumulated BPM in separate windows. The plugin also features a low-pass filter for greater accuracy, and can be reset from the GUI.
BeatCounter is free and is available as a VST effect plug-in for Mac OS X and Windows.