Cypocalypse's basic INTP guide to finding friends.
1. Deal with the possibility that chances are, fewer people will be likely to get in-sync with your INTP personality. But in my opinion, it's worth it even you'll end up racking fewer friends than not at all, even if it means you have to deal with a hugs majority that won't be able to understand you.
2. Force your untapped extroversion to come out. Chances are, at face value, INTPs can easily be mistaken by the general populace as an xNTJ, and that would mean we'd be pressured to be achievers or heavy doers like them. In my personal opinion, I'd rather be on the extroverted side trying to seek out people that would be attuned to me (at the risk of more people ridiculing me), rather than keep things at low key, where some of the people close to me would all of a sudden expect me to be decisively active in pursuing an ambitious achievement just because I'm perceived to be intelligent.
3. No matter how much you want to avoid them, chances are you'll have more SJ/SP friends or acquaintances than any other archetypes, especially the intuitives. If you're going to stick with a non-questioning, all-following SJ, for example, make sure that the set of cultural, community, family norms that the person follows is something that you can realistically deal with. It helps a bit if you're on the extroverted side because you can assert your personality better. My girlfriend, for example, is an ISFJ, and it's good that the norms she was following is actually pretty manageable, if not ideal for a long term relationship. My relationship with her has been really good.
4. SJ/SP friends aren't really that useless. Really. It's better keeping them with you aware that they're probably ridiculing you at any point than to keep yourself completely detached to them and keeping yourself isolated. For one, they provide a better template for public interaction (since they represent the majority anyway), and they're always a reminder for us to keep things light sometimes, because we're often serious. Though personally, they don't make the most ideal template for a long term relationship with the intuitives, but they're better off being kept in an acquaintance level, than not having them at all.
5. NF -- theoretically the best archetype for INTP friendship. Based on personal experience, they're the archetypes that try to connect with me on a personal level more than any other archetypes. I don't know what is it about my personality that seems to connect with them. I'm a blogger by the way, and for some weird reason my blog page has been attractiing some NFs. Anyway, I just blog bout anything. Sometimes, I deviate from my usual INTP way of writing (the observant perspective and all), and I try to mix it up on some occasions with personal sentiments. It gives my blogging a personal touch, though I hardly consider myself as the NF kind of poetic, or artistic. Still, it attracts the NFs.
6. If you're going to sign up in an online forum or any form of community, try signing up on those that are community based, where the likelihood of meeting people due to sheer proximity and accessibility is high, hence the likelihood of making the relationship transcend beyond the online set-up is good. And once that is established, you can integrate that with number 5 (e.g., providing a link to your blog page) so that you'll be giving a chance to those people to get to know you better.
I'll type more later.