Some excellent notes on using OFFSET and named formulas to help create dynamic charts in excel HERE

Here's a summary of the parameters available in OFFSET, courtesy of http://www.meadinkent.co.uk/xloffsetchoose.htm ...

"OFFSET returns a value from a cell which is at a specified number of rows and columns away from a particular cell reference. It is in the format: =OFFSET(BaseRef, Rows, Cols, RowRange, ColRange) . BaseRef is a cell address from which the number of Rows and Columns are counted (a relative reference) and can be located anywhere on your worksheet (although the top left hand corner of a table is conventional). RowRange and ColRange are optional and can specify a height and width of a range of cells (e.g. 4 rows high by 1 columns wide would represent all of the values for one of the months in the table below)."