Here is a collection of links that I use constantly.
If you are ever looking for an out of print book or would like to know the value of a certain book, Addall.com is the one I use.
It searches abebooks, alibris, and many more book websites all at the same time.
I find it works best by putting the author and title into the "keyword box"- that way if you have got the title slightly wrong you still find it - try it below.Prices are in Dollars but you can change the currency at the bottom of the page.
A really useful site for finding genealogical resources & information online is Genealogy-links.co.uk.
www.genhomepage.com The Genealogy Home Page
http://www.cyndislist.com A huge resource
www.english-roots.com Family history researcher for people wishing to learn about their English ancestors.Several free guides to research in England and Wales are available www.english-roots.com/Advice_and_Training/