Kenneth Sparr's Home Page A marvelous information site about the lute, the guitar and early keyboard instruments - particularly their history in Sweden.
Wayne Cripps' lute page A loose collection of lute related material and a lot of lute tablatures in "tab" format (can be converted to abc with "tab2abc").
bassus-generalis.org An amazing site crammed with 17th and early 18th C. basso continuo tutorials in html and PDF formats, translated into English, French and German as well as in their original language.
J. S. Bach - General Bass Rules An excellent introduction to the art of playing basso continuo mid 18th century style. For keyboard instruments, but lutenists should find this very useful too.