While our fancy calculators threw out numbers and could even deal with equations, there were no affordable tools that would actually draw a graph for you. 25 years later, all it takes is to type your equation in the search field and, voila, Google Search does it for you in an instant. If you use Chrome, you type it even in the location bar to see the graph. Gee, what would I have given for such a feature back in my high school days?
The Google graph drawing feature is a pretty powerful tool that supports simple numbers and exponents but functions such as sine and cosine as well. It won't be enough to do your homework for you, but it’s a good control feature and certainly a nifty free tool for math in higher education as well. And if you need a bit more features in the comfort of a good old calculator, you could always use an app or visit websites that offer calculators - and graph drawing engines such as web2.0calc.