That sounds like an easy job for the pgfplots package. Section 4.5 from the manual contains a lot of examples to start from, everything is explained from scratch and step-by-step. If you need more pgfplots examples, the section dedicated to plots at TeXample could be of interest. There aren't any bar plots, but it contains some nice (and more elaborate) examples of the functionality.
As for a code example, I could copy-and-paste one from the manual, but that would not add much to this post I believe.
Edit: when using Matlab, it is possible to use matlab2tikz. This way you can export your plots without having to worry about the actual code. Bar charts should be possible, but I haven't used that functionality yet so I don't know about any quirks. The plots I did export using this Matlab script were perfect and you get the consistency and flexibility you want :).
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