I carry a pencil in my EDB packet (a really small camera pouch I found at Target that fits easily in my pocket).
As far as pens go, my favorite and smoothest writing instrument is a plain old Parker $8-ish metal barrel model. Your standard click-in, click-out thing. But I wouldn't carry that in my pants or shirt pocket for fear of leaks.
That's why I now pocket-carry the Fisher Space Pen (Bullet model). Even if the thing leaked, it would be totally contained within the very tight fitting endcap. I had a Fisher Bullet Pen years ago and due to the pressurized cartridge, the tip of the pen would gunk up a bit and make blobs on the paper when you first started to write. I just bought a new Bullet Pen on a whim Saturday and while it's only two days old now, there is absolutely no indication of globbing like the old model. Either I've gotten lucky with this new pen (cartridge actually), or Fisher has improved their cartridges in the last few years. I've read of others having the ink blobbing problem in the past.
Let's hope my new one stays clean! I found it for $16.99 at
www.edcdepot.com In a neat camo coloring. That coloring is actually quite inefficient - who wants their dropped pen to blend in with the landscape? But it looks pretty cool!