I'm up for a new job and I qualify in every area except one... Excel. I have
good understanding of basic Excel features (I can build simple spreadsheets
and workbooks) but I need to expand this a great deal to have any chance for
the job (more advanced formulas, integrating with other apps/servers
etc...). I've found quite a few books, web sites, online classes etc... but
since time is somewhat a factor for me I was wondering if you could suggest
what you think is the one best overall learning tool for Excel?

Thanks!