Robert de Levie Advanced Excel for scientific data analysis Oxford 2004 (around $60 in paper).
Exellent discussion of VBA and something of its evolution. (Highly recommended)
     Tons and tons of good examples and listings
of running, debugged routines which can be downloaded (see following)
        fourier transforms
        error propagation and uncertainties
        creating buttons for various
tasks
     Tons and tons of useful routines already debugged,
downloadable from Oxford's site
          www.oup-usa.org/advancedexcel
Paul Kenton's VBA site www.vbaphysics.com (Highly recommended.)
Course notes for Computer Applications in physics.
A huge treasure of VBA instruction, mixed with physics problems and examples.
     He writes it's fine to use his stuff, but if
any financial gain is involved, he should be  compensated.
Kimmel, Green, Bullen, Bovey, Rosenberg and Patterson. Excel 2003 VBA Programmer's Reference
Wiley Publishing, 2004
Gets into the guts of VBA. Lots of stuff you won't need and quite a bit that could be useful if you need to do special stuff.
A little bit of stuff on VBA at www.rose-hulman.edu/moloney
    VBA Bits and pieces located in the Boise 2002 Workshop