I'm not sure if I can identify a rite of passage that I went through that made me feel like a man afterward rather than a boy, but I can identify a bunch of events that definitely helped.
Having sex for the first time didn't really do much to make me a man, but sexual experiences later on definitely did. The first time I woke up knowing that I'd made a mistake by having sex was important. The first time I had sex with someone I had fallen in love with was important. The first time I had sex with someone I was rising in love with was even more important. The first time I had sex with someone who was trying to teach me something in the process was pretty important.
Drugs are also kind of a big deal for me ... again, the first time I did hallucinogens wasn't nearly as important as a few of the others. My first experience with being in a state of mind I had absolutely zero control over was important, as was my first experience of being able to consciously control the output of my own sensory apparatus. The first time I ever helped a close friend through a tripping nightmare was important and definitely made me feel more mature and capable ... more adult, I suppose, though not "manly." My first drug-induced spiritual awakening was probably the biggest deal out of any single experience I've had in my life, so I guess that counts for quite a bit. My first bad trip was pretty important but by that time I felt like I'd already made the transition into manhood so I don't suppose it was necessarily a "rite of passage."
Going to Burning Man was probably the closest I've come to a "rite of passage" in the sense that it is a ritual that I participated in as part of an effort to make me more of an adult. It worked, I think. The second time worked WAY more, I'd say (big long story about that, you can dig it up in the polyamory thread in "DISCUSS").
I think it's a problem, to some extent, that we don't have any culturally agreed-upon rituals for bringing someone into adulthood ... but really I only say that because we just don't have any that I personally believe to be more important than any of the others. Obviously people still have bar mitzvahs and 18th and 21st birthdays and that sort of thing, and treat them as being important in one's rise from childhood into adulthood. But if it were up to me, it'd be like in Island by Aldous Huxley, in which every child in the society goes through a yearly ritual at about 17-18 in which all the kids of the correct age tie themselves together and climb a cliff as a team and then take mushrooms and meditate at the top.