The alphabet in light writing, found on Nir Tober’s Flickr.
The hairy Futura typeface, found on Behance.
Human crafted typeface, found on Hijack Your Life (link removed, no longer working) via Brand Flakes for Breakfast.
Eine’s East End of London shopfront shutter letters, found on Dave Gorman’s Flickr pages.
The Alphabet Photo Gallery by Abba Richman at pbase.com (link removed, no longer working).
Inspired by Abba Richman’s collection, prior to this, Thomas Fredriksen created his own alphabet photo collection on pbase.com (broken link removed).
If light writing is your thing, here’s a post with some light writing YouTube videos.