Mikko Maducdoc has released a beta version of Milk Guitar, a lightweight strummer plug-in that can help create realistic strumming patterns.
Easy-to-learn pre-defined combinations allow you to play chords, and special keys allow you to strum and tap the guitar. It has built in effects like reverb, filters, and stereo-widening.
Milk Guitar is free and is available as a VST instrument plug-in for Windows.