I am a SAHM now to two children, but wasn't always. I worked full-time outside of the home until my son was 13-months-old. I've been a SAHM now since March 2006 -- now to my son who turned two in February and my daughter who is 5-months-old.
I love being able to stay home with my little ones, but it is a VERY busy job! ;) They keep me hopping throughout the day, and we try to get out and do lots of things (to keep me sane and them entertained)! That can sometimes be more trouble than it's worth with two, but you'll be able to enjoy a lot with your two-year-old this summer! ;)
We are involved in some playgroups so my son can enjoy time with friends his own age (and I can enjoy the company of other adults, too). We have been to storytimes offered by our local library, free Kindermusik classes, and are planning to check out the free movies offered at the theaters here this summer. We go to parks, to the fountains (there are several in our area for kids to play in), and the zoo.
Look in your local paper, on Web sites and ask friends about things to do in your area. It took me a while to learn about things to do in our area after I started being a SAHM. I hate you lost your job, but I hope you enjoy the time you have this summer with your son! Have fun!