The Scheme language and the excellent textbook used for it, Structure and Interpretation of Computer Programs, which also makes a good, general-purpose computer programming textbook.

Here is S-Lang, a C-like embedded scripting language.

The ultimate scripting language reference! http://www.softpanorama.org/Scripting/index.shtml. Compares 'n contrasts 'em all, complete with beaucoup references for each language.