If you work for a hospital, school, college or non-profit, they may offer a 403b retirement plan.  A 403b is very similar to a 401k plan and has the same contibution limits, often they do have higher fees and have annuities as investment options.  Make sure and exaimine the investments they offer:

These teacher-retirement plans often limit their offerings to insurance products, such as annuities, and they charge much higher fees than 401(k)s. But the biggest difference is the way 403(b) plans are sold. Instead of a menu of funds -- with easy access to information about fees and perform­ance -- many school systems just hand out a list of sales reps. 

Some hospitals and colleges match 403(b) contributions, but most K-12 public schools do not. If your employer matches your 403(b) contributions, invest at least enough to get the full match -- that's free money. But before you put all your retirement money into a 403(b), do a little digging:

Compare investment choices and fees. The range can be huge. Some plans have fees as high as 2.42% per year -- for the investments and annuity charge -- and have a surrender charge if you cash out before eight years.   But others, such as Vanguard, may offer a target-date fund (a diversified portfolio that gradually gets more conservative as your retirement date draws near) with a 0.20% fee and no surrender charge. TIAA-CREF charges from 0.42% to 0.92% for its funds, and 50 cents on a $10,000 account for its annuity expenses, with no surrender charge.

Kiplinger Offers 403b Tips