Thanks a lot for your answers!
@frob: I've got a basic understanding of software rendering, I got no problem with transformation matrices etc., and I know how to render a single line, maybe I could learn a bit more about texturing, lighting and clipping - but what I want to take a look at is a pretty simple software renderer - without any effects etc. - just the basics. I've already written a pretty simple soft renderer - but it wasn't in C++. So I just wanted to see the different ways people write a software renderer (I mean I'm not really acquainted that much with what is considered good practice when writing such a program). I really wanted something simple - not really the Mesa soft renderer.
@zacaj: Thanks a lot for the renderers - I'll look through them. And yes I would be really glad if you could post the renderer you are coding - I don't really care about compiling - I just want to analyze the code.
Btw - what library would you recommend for a SetPixel(x,y,r,g,b) like function - SDL? (I really am not that acquainted with the libs for C++)