Going the really EZ - cheap way - mix up some clorox outdoor with a bit of dawn dishwashing detergent. We don't use it, but there are plenty of folks that do who do a fine job.
Another - go to home depot or lowes and grab some Zeps all purpose pressure washer detergent. It's pruple and comes in 5 gallon jugs for $29. While its no super hero - it does a good job. Same goes for Zeps all purpose concrete clean - which you can also find at home depot or lowes.
Going a bit further - we recently started using Citracleen for houses. It's about $50 for 5 gallons but you gotta order it in TN so shipping can easily ad another $20 - $30. It is a good cleaner and probably one of the most recommended.
There's another thread on here called "concrete cleaning" that several of us have been duking it out about which is the best technique for cleaning concrete. Some say chlorine, some say acid - I still say in most residential cases - a turbo nozzle, a basic detergent and some skill.
