Meeting like-minded people for forming collaborative research relationships
In reality collaborations come easier to some than to others. Here are the factors I found help most:


Be a member of the community. Go to conferences, give talks (or present posters, or demos, or whatever else is common in your community), organize events and workshops. Talk to people about your work. A first step towards collaboration is that others need to be aware that you exist, and what you are working on. Once people are aware of your work, chances are somebody is working on a related problem and would like to know your opinion on it.
Be a nice person, and make sure that you are pleasant to work with. When you collaborate with somebody on anything, make sure to be constructive and deliver what you promise on time. News travels fast about collaborators who have a tendency to be overcommitted or who use collaborations mainly as cheap paper producing machines.
Have ideas. You say you don't want to go around asking whether people "need help" - well, no, you should not - collaboration is not a consulting service. You should listen to their current work, and propose directions that combine their problems or expertise with yours.
Have uncommon (but helpful) technical or methodological skills, and be sure that people know about them. If all you can do others can do similarly well, why would people want to collaborate with you?
Have access to data that others don't have access to. This may be a proprietary data set, but it can also be that you just understand a public data set very well and have good tooling to effectively work with it.