I also occasionally struggle with wanting to be social without needing to spend too much money at overpriced bars, restaurants, etc. I definitely support more house/apartment gatherings and when the weather is warmer here my friends and I often go on "beer walks" at night, walking around the city, maybe stopping in a park and just talking while drinking cheap beers from convenience stores along the way (I realize this may not be legal in many other cities). I've been cutting back on beer but a flask and buying cold mixers along the way works just as well : )
I try to avoid dinner dates (esp. first dates), but not just because I'm a cheap bastard. I find them more awkward, since you have to keep conversation going for long periods of time while simultaneously managing to chew. I've never felt that you actually get to know the person better while eating than if you just had a round of drinks. The reduced time commitment and low pressure of just having a drink together makes it easier for both of you to relax. Nothing worse than a horrible dinner date that drags on so long that you actually can't wait for that huge bill to arrive just so you can pay it and get out of there.
A final idea that keeps my social spending lower may be a bit trickier for some to implement, but it works for me. I have two hobbies which allow me ample time to socialize at bars, usually for free. I play music with some local rock bands. Whenever I play a show, I get in for free, get to check out some other local bands, and usually get a few free drinks from the bar and a little bit of money from the door. I also perform standup comedy and organize a weekly open mic. I get to support local comedy, meet funny people, and get a few free drinks as well. Between these two hobbies, I've usually got 1-2 nights out a week without even touching my wallet.
Even if getting on stage frightens you, you might be able to find ways of getting involved in other events that match your interests, even if it's just volunteering to help out in exchange for free entrance, etc. Of course, I should warn that spending a lot of time at bars makes it more tempting to buy more drinks, especially when you're in the mood to celebrate a good performance. When that does occur, however, I'm much happier to be doing my spending at bars that support events I enjoy.