What are some good (ideally free) tools to give laymen access to basic statistical techniques? I have been a contract worker for two different companies now, which means I show up at a place for 3-6 months and blow their minds with my awesomeness, but then, to everyone's disappointment, I leave. This is great for me, since I get a new workplace with new problems, but it can be troublesome for the place I left, since they no longer have a person that does something more than look at pivot tables.
In an effort to add more value to the places I work, I have started looking into ways to help business people step beyond just pivot tables. Obviously my goal is to not send my nice coworkers off into the woods without any knowledge, but rather to teach them the basics of regression, some graphics options (really pulls a lot of weight in the business world) and maybe some kind of classification (thoughts on what you think is most relevant would be great) in a weekly/monthly meeting. I am picturing an intro level statistics course for an undergrad, which while long ago for many of us still offers quite a bit of power over something like little green arrows if there was growth at all and little red arrows if there was decline next to an excel spreadsheet.
I am an R person myself, so I have been looking at the different options there, but I am not going to limit myself to just R, so don't let my list limit you. What I have come across so far:
http://en.wikipedia.org/wiki/RExcel
I am waiting on IT to give me permission to install this, but it looked promising to me. Excel is the life blood of the places I have worked, so if there is an easy way to get them access to R as an add-in it would help get over the hurdle of learning something new.
http://rattle.togaware.com/
I have played with Rattle some and generally had a good time with it. I think it is a bit beyond what I had in mind in terms of statistical difficulty, but it is put together in a very appealing way.
 A: Judging from my experience with research-active clinicians, imparting safe levels of statistical knowledge is very, very difficult. In 3-6 months while doing other things I would hazard that it's impossible.
I think in your shoes I would just make a lot of reports that write themselves (with Brew, Sweave, R2HTML, whatever) and go HEAVY on the visualisations.
Anything else and you're just putting a loaded idiot-gun in their hands.
I would also wean them off Excel. Just get them using .csv files, in Excel if they wish. Proprietary file formats, merged cells, coloured cells, they're all the devil's work. A nice, flat, colourless, .csv, that's all they need.
A: As I said in my comment, my first concern would be that you need to figure out how to avoid making people more dangerous by handing them tools that are more impressive than Excel but that also require a lot more knowledge/intuition/experience to properly use and interpret. Sort of like replacing company cars with airplanes.
That said, I have always had a bit of a soft spot for gretl. It's command-driven (like SAS, et al, and as opposed to R) rather than a language, has a reasonable GUI and is pretty powerful.
I can see you using graphical flow tools, like Rapid Miner as well.
A: When it comes to data mining, Weka is very user-friendly.
