Tubeless Tires (Especially Bontrager's TLR System) For Mountain Biking: There was a time when I was highly skeptical of the whole tubeless tire technology thing. The system that changed my mind, and that I think is still the best, is Bontrager's "TLR" system for 29"ers. It is bombproof in my experience. I did have a couple of hiccups with it at first, but ever since the first go round, I have been totally impressed with this tubeless system. I like others as well, but Bonty's is still the best.
Ergon Grips: (Especially the GP-1's) I have been riding with Ergon grips since 2005 and I wouldn't ever go back to traditional round grips. I have tried almost all of Ergon's grip styles, and I like all of them, but the first is still the best. The GP-1's I first started using in 2005 are still going strong in 2010 on one of my favorite bikes. Pain free hands are awesome to have on mtb rides. I thought it would never happen, but thanks to Ergon, it did for me.
Oakley Jawbones Eyewear : I have been wearing these for a year now and since the time I got them, I wore nothing else until a recent review assignment that I had to do on another brand. I'll tell you what, nobody nails optics like Oakley does. Nobody. Plus, add in the lens features that repel sweat and moisture, the anti-scratch feature, and the nose and ear materials that Oakley uses, and it is a no-brainer. Expensive? Brutally so. Worth it? Absolutely. They are my eyes for crying out loud. It isn't like I can get more eyes if I don't take care of them.
Ragley Carnegie's Bar: You know, when I get back to riding one of the two rigs I have set up with the Carnegie's Bars on them, I realize all over again how much I like these. The sweep is right in the sweet spot, and my control over the bike in corners just feels right with the Carnegie's.
Don't get me wrong, I still love drop bars, but if I have to ride a non-drop bar bike, these are my favorite bars yet. Now in carbon, which have a nice amount of give too. Sweet!
OS Bikes Blackbuck: If I had only one single speed, this would be it. The OS Bikes Blackbuck isn't a "high end" rig, it isn't made of the latest "unobtanium" frame material, and it isn't some high cache' custom frame builder's rig. It is a frame with some style and functionality to boot.
Not only that, but it is super versatile and can be set up with all sorts of forks and handle bar set ups. (Just ask me!) Good news: OS Bikes should soon have the "Gen II" frames in stock in three different sizes!
Salsa Cycles Fargo: And if I had to whittle it down to only one bike? This would be the winner. The Fargo can do it all, and do most of it as well as any bike can. I can single track it, I can gravel grind it, I can road ride it, and I can commute it. Hey, it's even pretty dang good at all of that as well! Maybe it can't do the "big" stuff off road, and maybe it's overbuilt to road ride, but between those margins, it has you well covered. Bonus: This bike, for whatever reasons, hits me as the most comfortable, best fitting bike I have. So much so that I am afraid to change anything on it! (But I still do, occasionally.)
And there you have it. Six things I can think of straight away if you ask me what are my favorite bicycles/bicycle related products. There are more things that could be added to this list, but not many that I think are almost perfect and would be very hard to improve upon.