On the pencil side, I've bought in my youth with my own pocket money (huge investment at that time) a Rotring Tikka 0.5mm that I'm still using today. Very nice tool full of German mechanical goodness.
Otherwise, I'm a huge fan of fountain pens. My favorites are a Sailor Professional Gear - super quality, very fine trace, strong black ink, incites to a careful and deliberate writing and a vintage Pelikan M400 pen with a custom nib (yes, I'm a pen snob, I know it) - generous trace, smooth gliding, very good for day to day stuff. The Sailor is perfect for fine annotations, schematic notes, etc. The Pelikan has a nice plum ink and it's quite elegant.
(Don't get me started on ink/paper combinations).
However, I must admit that I'm not manually writing too much these days. I largely prefer some computerized (PC, tablet) method together with Palm notes/OneNote/Evernote apps. I absolutely like the fact that I can quickly update/modify/transform the information, save it, having it synchronized on several devices, etc. Even for home, I prefer storing stuff in OneNote (and previously Palm notes - just recently, I've consulted the pinout of a home automation device that I've made back in 2001). My old notebooks are really crusty and they should be somewhere in storage.