Debra Auerbach included some of my tips in her great article for MSN Careers / CareerBuilder on how to negotiate non-salary benefits. She gives a nice overview of the different steps to make the negotiation process as smooth as possible, and includes a list of some of the benefits candidates can successfully negotiate.
Some of the negotiables mentioned in the article include the job title itself, vacation time, profit sharing, advance degree / training sponsorship, severance / outplacement packages, housing subsidies, wardrobe allowances, child care subsidies, and transportation benefits. Another major area for negotiation can be the work hours / flexibility to work from home.
Tips for negotiating: do your research, know what you want and what you are really willing to take, and plan ahead! You can negotiate to ensure you'll have another opportunity to negotiate again soon - whether that's a 6-month performance review or a guaranteed salary bump/bonus when you meet a certain productivity goal.