(Advanced Calculus by Kaplan; great book for math majors)

http://www.amazon.com/gp/product/0201799375/104-2187716-1541559?v=glance&n=283155&s=books&v=glance

(Geometrical Vectors by Weinreich; advanced text for math buffs)

http://www.amazon.com/gp/product/0226890481/qid=1134722786/sr=8-4/ref=sr_8_xs_ap_i2_xgl14/103-5899645-7966249?n=507846&s=books&v=glance

(A History of Vector Analysis by Crowe)

This book goes pretty deeply into the subject. For math history buffs. Cheap!

http://www.amazon.com/gp/product/0486679101/qid=1134722175/sr=2-1/ref=pd_bbs_b_2_1/104-2187716-1541559?s=books&v=glance&n=283155