As described in detail elsewhere, in January, 1987 I witnessed a pair of glowing red spheres at relatively close range, as they crossed the sky of southern California, west of El Centro. They overtook me from behind, passed directly overhead, and then continued on in front of me for several minutes before I lost sight of them in the distance. I was not abducted, nor did I suffer any ill effects, except for lingering anxiety and fatigue.
Did this event change my life? Yes and no. Except for the fact that I determined, the following day, to pay a visit to the area where I'd grown up and a few of the people I'd known in my youth, there was no immediate change that you could point to. I returned to the same community where I'd been living and to the same job I'd left a short time earlier. But one thing was plainly different; I no longer had the luxury of scoffing at those who claimed Earth was being visited by extraterrestrials.
Many years later I happened across the web address of the National UFO Reporting Center, and saved it, only later making use of it to file a report. This weekend I discovered the existence of the Mutual UFO Network, and again filed a report (getting a few details mixed up on the first attempt).
Looking further into the various organizations, I've arrived at the opinion that MUFON is probably the most credible of them, that is if you like your UFO accounts unmixed with talk of advanced technologies (which, if developed, could render efforts to develop renewable sources of energy unnecessary), grandiose conspiracy theories, and cosmic consciousness - not that there aren't conspiracies or that there's anything wrong with cosmic consciousness.
If you aren't put off by the tangential connections mentioned above, then you might also find Center for the Study of Extraterrestrial Intelligence and The Disclosure Project worth your time. Both of these are headed by Dr. Steven M. Greer and inevitably strongly reflect his own belief system and concerns. Even if you find his forays into such subjects distracting, Dr. Greer's credibility is impeccable as compared, for instance, with Tom Cruise.
On the other hand, if you're a storm chaser at heart, you'll want to go straight to the latest reports page which lists the 20 most recent sightings reported to MUFON. Don't forget to bring your video camera! Be warned, some of them are bogus, and some relate to events that happened months or years prior to being reported, but there's enough left to keep you very busy.