I've been using an Astronomy book called Universe, 7th Edition for the last year and a half as reference material for the Astronomy course I am studying at University College London. It's taken a while to fully appreciate this book and it was only when I managed to complete a few home works that I realised what a superb book this really is. It's pitched at the under graduate student with a lot of excellent supporting material such as a CD ROM and hyper link references to extra resources on the publishers web site which directly relates to material in the book. The style of the book is very accessible and it makes subjects such as neutron star formation and stellar evolution quite easy to understand. The book covers a wide sperad of topics ranging from the basics of SI units, distance, time and angular measurements to the solar system, stars, galaxies, the interstellar medium and beyond. There is a fair degree of mathermatics in this books but nothing beyond basic high school algebra. If you're after a book to support your learning, this is a good one.
A regularly updated blog about Kaustav Bhattacharya's Astronomical observations through his Meade ETX105 telescope and general views and comments about Astronomy.