Boots of Elvenkind were probably inspired (like most of the original aspects of D&D) by J.R.R. Tolkein's Elves. Although not as important in the books (and movies!) as the Cloaks of Elvenkind, the boots are definitely responsible for part of the famed Elvish stealth.
In the new Dungeons & Dragons 3rd Edition game:
Boots of Elvenkind: These soft boots enable the wearer to move quietly in virtually any surroundings, granting a +10 circumstance bonus to Move Silently checks.
Caster Level: 7th; Prerequisites: Craft Wonderous Item, secret page, creator must be an elf; Market Price: 9,500gp; Weight: 1 lbs.
These are often used in conjunction with a Cloak of Elvenkind.
Update 9/16/2003: Ouroboros says re Boots of Elvenkind: Would you take note of the 3.5E changes that set this to a +5 bonus?