craigslist.com, craigslist.com, craigslist.com - find your city or general area. Plenty to offer.

Or, go to your local Unitarian church (if there is one) guaranteed to find like-minded people off doing all sorts of stuff thats secular and fun.

citysearch.com may also have stuff.

I feel your pain. I always feel like I "waste" my weekends. But then I remind myself that I'm an overacheiver and sometimes being a lifeless blob is just what I need. Balance. But when I really want to get out of the house, I lure myself with FOOD.

I usually don't get moving on Saturdays until 1 or 2 in the afternoon. I feel a little guilty but I work pretty hard during the week and need to decompress a little before I can start thinking about house work and such.

Why not start your own group? Then you'll be sure that it meets every Saturday afternoon.

I highly recommend a yoga class. I don't know what the selection is like where you live but hopefully you'll have some choice on the hour & location. Make it in the morning, but not so early that you'll be tempted to skip it. It will give you something to do, you'll be around other people, and it will bring energy and a sense of well-being to the rest of your day. Not to mention a nice feeling of having accomplished something. The class I go to is extremely mellow - it relaxes me as much as it energizes me. It's completely compatible with my own tendency to take it super-easy on the weekends.

Thanks a lot for your suggestions guys. I actually did come up with something - I forgot that an indoor ice skating rink not far from me has public ice skating sessions early Saturday afternoons. That should be enough to float my boat. ::keeps fingers crossed::

Meetup.com might be good too. My Flickr group (where it seems I spend most of my social time these days) uses Meetup.com for its events.