What can't you do in Excel?
ecommercematt: In no particular order, here are some desirable features:1) Version control. 
2) Access restrictions and permissions. BONUS: Responsibilities, a la Siebel and other CRMs. 
3) Simple drag and drop manipulation of data, such as concatenation. 
4) Wufoo-like ease with building data entry forms. 
5) Dummy data mode, so you can get help with customizing a complicated spreadsheet without revealing sensitive data.
6) Example use cases for sophisticated features, with well-written instructions, INOW a good, non-linear tutorial.