I have written an upper-division undergraduate textbook,
A Friendly Introduction to Mathematical Logic. (Prentice-Hall,
2000), which is unfortunately out of print. Instructors who might be interested in using the text should send me an email.
There is an errata sheet for the text, which
is a .pdf file. If you don't have a .pfd reader and can't get the
free one from Adobe.com, send me an email
and I will gladly fax you a copy.