A lot of people have to use tools or supplies in their work that aren't provided for by an employer. Consider contractors: While they might rent a lot of heavy equipment, it certainly behooves them to have a good supply of their own tools around. If your equipment reaches its useful life before the year is out, you can write it off wholly on your taxes. If not, you'll have to depreciate the purchase over its useful lifetime. (That means you'll need to write off a fraction of the cost over the course of a few years.)
Even if you're not self-employed, you can still write off some tools and supplies if you're buying them out of your own pocket. Teachers or educators, for instance, can deduct up to $250 of their adjusted gross income for supplies they bought for their classrooms that were not reimbursed [source: IRS]. You can also deduct uniform costs if wearing one is part of your job requirement.