I find the official BOM template to be somewhat annoying to work with for two reasons: 1) The small, blank columns require me to hit a few extra arrow keys each time I enter a part, and they prevent me from effectively using shortcuts like shift-right, which adds up when I'm entering a hundred parts; 2) I always have to add more rows to some of the subsystems and then repair the formatting and subtotals afterwards.
So I used a very simple BOM format instead (blank example attached). It was faster and easier. I added a grand total at the bottom when I was finished.
2012 Unofficial Alternate BOM Template.xlsx
Edit: Excel 2003 version:
2012 Unofficial Alternate BOM Template.xls