For instance, if you're applying for a media-buying job, and you worked as a radio dj in college, that could be relevant. If you're applying for a position with a firm that markets outdoor sports products and you have extensive backpacking experience, they'll be happy to know that. Point out interests or abilities that entail skills the employer may be looking for. Playing chess at a high level indicates an ability to think in a certain way. Traveling extensively on one's own implies a certain wherewithal or savvy.
Athletic achievements point toward goal-directedness and a familiarity with sacrifice.
Social memberships tend to indicate an ability to communicate. Point up your skills. If you like to write and are good at it, don't let that escape notice. A few final words. Don't include a work phone number.