Scheme tutorials and reference
You may find some of these useful. Although I should note that I am
writing my own Scheme handouts because I'm not really happy with any
This is a fairly extensive reference and tutorial for Scheme. There are a lot of things I like about it, but it is a bit long, and some sections are not filled it. One thing that I don't like about it is that in the beginning, it translates C/C++ statements and expressions into Scheme. I think this is a mistake because this approach does not carry over into Scheme procedures of even simple to moderate complexity. You need to give up thinking procedurally and think functionally instead.
This is a nicely done presentation of Scheme that is a pretty good cross between a formal presentation and a tutorial presentation of the language. My only complaint is that it quickly introduces "advanced" features of the language pretty early (such as dotted pairs and mutators), whereas I'd rather focus on the main features that you need to know to start writing programs quickly (and in a functional programming sort of way!)
A concise tutorial which has a somewhat formal presentation.
Has several sets of exercises with solutions.
Links and Scheme propaganda
I should really update these...