My first few years I was creating everything in Word (oh the humanity). Even with MathType as an extension, it was so tedious.
A few years later, we adopted math curriculum that included Examview. I used the provided tests and quizzes, but also had the ability to create my own assessments with its built in equation editor and even include graphs!
About five years ago (???) I stumbled upon Kuta Software! Do you hear the angels rejoicing....
They have free worksheets available to download with answer keys.
More importantly our school purchased the software (available from Pre-Algebra up to Calculus) and it has changed my life. It is so easy to create a worksheet/quiz/test and have the ability to recalculate and scramble questions for multiple versions. The software also has a presentation mode that you can display on your projector. I have the students use individual whiteboards to work the problems out then we can go over them as a class.
Check it out...it will change your math teacher life!