Here locally, there are a couple of websites that list them all. You might try googling around to see if there's something like that for your area.
Also, bicycle club websites often have listings and links for the rides they will be involved in. You might also check at local bike shops.
Events are not always planned out as far ahead as you might think. Last time I checked, there were several north Texas rides that hadn't posted their event dates for summer 2009 yet, although the event is probably happening.
__________________
"be careful this rando stuff is addictive and dan's the 'pusher'."