Feats are one of the things I like least about 3.x versions of D&D. They are one of the things that really help turn the game from a game of action and adventure, to a game of trying to design the best character. However, a lot of feats have been created over the last 6 or 7 years and many of them are quite interesting — if one just did not have to deal with the problems the 3.x Feat system brings. For example, here’s a feat from the 3.5 SRD:

Dodge [General]
Prerequisite: Dex 13.
Benefit: During your action, you designate an opponent and receive a +1 dodge bonus to Armor Class against attacks from that opponent. You can select a new opponent on any action. A condition that makes you lose your Dexterity bonus to Armor Class (if any) also makes you lose dodge bonuses. Also, dodge bonuses stack with each other, unlike most other types of bonuses.
Special: A fighter may select Dodge as one of his fighter bonus feats.

The Dodge feat could easily be turned in a magic item for use in older versions of D&D. For example:

Hairpin of Dodging: This ordinary looking hairpin allows the wearer a -1 bonus to his or her AC against one opponent when worn. The wearer may designate the specific opponent each round by saying he/she will dodge when attacked. This bonus stacks with all other AC bonuses, including other items of dodging. The character must be capable of movement to be able to dodge.

Many feats could be used as magic items. Ones that add special knowledge like abilities might make great Ioun Stones. Others could be rings or unusual, unique items. Using feats this way puts them under control of the GM while presenting ideas for hundreds of unique magic items, many of them relatively low-powered.