I need the ability to look data across multiple worksheets. In essence, I
need something like VLookup or HLookup, but I need a 2-dimensional search
across (a) a given row or column on one worksheet and (b) the same row/column
in each worksheet in a defined group --, rather than 2-dimensional across a
row and column, as in VLookup and HLookup.

Any ideas?