H.W.
I recently joined Mothers and More and I love it! They have playgroups, mom's nights out, couples activities, family activities, a book club, and lots of other activities. You just join and attend the things that interest you. I feel like I'm in a community of moms now. There is a yearly fee, but I think it's totally worth it. Plus you can attend up to 2 meetings without actually joining to see if you like it. I belong to the Grand Rapids Chapter, but the group is in other areas too.
Here is the main website: http://www.mothersandmore.org/
and this is the Grand Rapids chapter website: http://www.grmothersandmore.org/