Last year I made friends with a few moms from my son's mother's day out group. We'd chat in the parking lot a little and then one day one of the moms said "hey, how about Starbucks after dropping the kids off next Tuesday?" and we went, invited the other moms in the parking lot, had a nice time. Then I invited the moms to my house after dropping the kids off a couple weeks later. It was pretty organic and basic, but that's what we did. Then when something special like Thomas the Train, The Wiggles, or Walking with Dinosaurs came to town, we made sure to say "Hey, we're going to this....are y'all? Wanna meet up?" Sometimes it worked, sometimes it didn't. But by the time summer came around, we were able to say "hey y'all come to my summer party at the water park" or we went to someone else's spraypark. Also, a lady I became great friends with at Bible study (over the school year) kept her granddaughter, my son's age, and when Bible study ended for the summer break, we met up a couple times at a playground or her backyard for a playdate, then I'd invite her to lunch for Mexican and she'd invite me for Egyptian, and we had great fun. The kids became great friends. On my son's soccer team, there are 2 moms that I've made casual friends with, and we have already had 1 playdate and plan on going swimming and also having a summer party at my new house after the season is over. Both moms have boys my son's age (on his team) and also have younger siblings for my younger son to play with. It's not really an accident though. I place myself in situations where I will meet moms with children my kids' ages so that they CAN have playmates. Don't know what there is to do in your town, but if you have a free magazine at the grocery store or doctors offices similar to Suburban Parent or Ft Worth Child....something that's a free parent's magazine, you can find loads of things to do for fun all summer long there.
Last year's summer was in a town that was AWESOME for families with smaller kids. Our routine every single week was basically something like Mon: off, nothing.....Tues: go to the playground behind the library for 30 minutes, walk to the library for storytime and a little craft, drive 2 blocks over to McDonalds for small fry club (a free club in the indoor playland that had a story, a craft, some songs, special guests like Ronald or firefighters or whatever)....Wed-Fri would be a playdate and/or a trip to see something (zoo, ride the train, go to the airport observation park for a picnic and plane watching, explore downtown and see the water gardens, museums, art galleries, or just get ice cream and walk around, go to the stockyards to be a cowboy, etc)....weekends: family outing to Botanical gardens or nature trails, take a trip to a safari, a fair or festival, the farmers market, a play at the children's theater, church, volunteer somewhere, and time at the community water park. We would swim 4-5 days a week every single week in the evenings when daddy got home from work. This year....we've moved to a much smaller place. We will do playdates occasionally, we will explore the new area, go to the beach and nature preserves, and on weekends try to see what's going on (whatever the local event is at the moment: one weekend it was an equestrian show and a yacht hop, we loved them both...this weekend it's a dolphin cruise (half price) and tomorrow is an art festival....etc) Have fun, whatever you do!!!