One of the hardest things for me to get used to since we decided I would the the stay at home parent was the reduced amount of social contact compared to when I was working. I'm still not sure I'm quite used to it.
Maybe if you could fit in a part-time job of some sort into your routine, it would be good for you. It could be a job related to something you like to do, and then you'd have a shared interest with the folks around you too.
Depending on how old your kids are, get involved with their activities. You will have plenty of occasions to socialize with other parents, at the very worst there is always a common subject, the kids.
