This webpage by a Sealed Knot Parliament unit is superb. It's what a Civil War reenactment website should be like in my opinion - great photographs that really capture the atmosphere, lots of historical background and an attractive layout makes this a page well worth visiting. I also like the idea that they sometimes portray different units at different time periods in the ECW. See them this weekend at Bovington Tank Museum (Dorset).
Also on this weekend at the Cromwell Museum Huntingdon is a large ECW wargame of the ECW...more here