Within an HSA, you should have investment options such as mutual funds or brokerage/equities, in addition to the standard savings account/money market.
I think *most* HSA that are funded via paycheck deductions have ability to put $ into mutual funds.
I can say that the options provided by the plan my employer uses are horrible for fees / minimum investments.

*However*

HSA funds belong to the account owner.
SO - I can take my HSA money and take it over to my local credit union and put it into an HSA account there (they have no investment options IIRC, so probably not a great choice. But I think their fees are very low.)

OR - I can take it to another bank/investment company and get better options for investment (looked just now, and http://www.hsaadministrators.info might be an option -the $45 + $3.20/$1000 in annual fees isn't too terrible. And they do have a S&P 500 fund. )