Here are some things you might be able to negotiate with a potential new employer especially if salary negotiation isn't something they will entertain:
Job title
When I started as a recruiter, the first time I filled a job and got someone hired, they got to choose their job title. It doesn't always happen of course, but in this case my job candidate asked, and got the job title he wanted!
Job responsibilities
Perhaps the actual responsibilities of the job could be increased. I've seen it happen.
Bonus amount
You might be able to negotiate the amount of the bonus or perhaps the percentage.
Bonus frequency
Perhaps you can increase the number of times the bonus is paid to you.
Signing bonus
If the employer won't agree to an increase in salary, perhaps a one-time signing bonus might be doable? I've seen signing bonuses used to bump up a person's first year salary. I once got a signing bonus for a job candidate when the company was unable to increase his salary.
Vacation time
Can you get extra vacation time? Perhaps a few extra weeks or longer might be negotiable?
