Excel 2007 introduced the new interface called the Ribbon. It’s a cross between a toolbar and a menu. It also has a Quick Access Toolbar (QAT) that many people don’t seem to be using.
Excel allows you to easily hide a group of sheets BUT frustratingly, it won’t let you unhide a group of sheets. You have to unhide them one sheet at a time.
Make Your Own Lists like January, February etc
When you drag a cell with January in it with the fill handle (the small cross at the bottom right corner of the cell), Excel creates a series with February and March etc. This is quick and useful. It also works for days of the week. Eg drag a cell with Monday in it to get Tuesday, etc. This is an example of a custom list.