Knowing I wanted to found additional startups I always had my eye out for a great partner. I wasn't finding anyone I thought met all the criteria, yet I held fast to my commitment to not make the same mistake again. Ideas came and went but I was determined to not start by myself or with the wrong person.
Last summer I met a guy I could work with. We completed a detailed project and then decided to apply for Y-combinator. Nothing was done by either of us to facilitate finding this relationship - in fact it was almost by chance that we met at all - however it's clear after only 6 months of working together that it works. When it works it works.
My advice is to be patient. Never force the relationship. Network - but do it to meet new people not specifically to find a partner.
The only people who will react favourably to this kind of approach are the ones you definitely don't want to marry or start a business with.
Personally I don't recommend going out and look for partnerships. Its an easy way to get into a co-founder battle or have different interests that you only discover 2 months later. All those successful partnerships named early on are people who knew each other better than they knew themselves or just worked really well together. Going out and just networking isn't going to get you such a relationship. What you need to do is form a deep relationship and constantly shoot the shit and work on projects together, that way you can determine weather you work well or not (schools and living together are all things you can do this at, and is also common among all the successful partnerships mentioned above).
