1, Collimation (or alignment)of a telescopes optics guide, from the sky at night magazine
Instructions on how to align (Collimate) the optics/mirrors on a reflector telescope
2, Altair CMOS camera instructions and help
Makers of astro telescope cameras
3, Astronomy Tools Useful Telescope calculators
A rather excellent resource that will give you an idea of all kinds of measurements for Telescopes and astronomy
4, Back Yard Astronomy Group
A great group forum for armature astronomers