I unfortunately don't have the time to idly surf about like I used to, but I still get around to it every now and then since there's just too damn much cool stuff out there.
This time 'round, I chased a couple links off of Hackaday, and happened across two interesting motorcycle projects.
One, the better-illustrated of the two, is the rebuild of a 1921 Ner-A-Car, an odd and rare American design. Wiki Link for those interested in more info on the brand.
Basically, the guy got the proverbial box of scraps, and had to fix or modify- or make from scratch- virtually the entire motorcycle. He even successfully tried his hand at metal spinning to form the headlight buckets!
Haven't had a chance to go through the entire build yet, but what I've seen so far was pretty impressive, if a little lacking in photographic detail.
The other is an article by a fellow, presumably in Buenos Aires, who bought a motorcycle years ago, which had been badly modified. In researching how to fix the mod, he decided to develop his own cylinder head- among other things. Eventually he milled his own DOHC cylinder head, added electric start, modified the ignition, made his own connecting rods, balanced his own crankshaft, and eventually even designed and built his own fuel injection system.
Unfortunately the page is either a bad Google translation, of the guy himself only has a moderate understanding of english, so the descriptions, which I suspect were already vague to start with, take a little mental parsing to understand what he was trying to say.
Still, remarkable and impressive work, and worth a look.