You can set any size for a sidebar (read more about sizes). Sidebars can be specified, for the whole site, for each category or page type, or individually for each page / post. You can create as many sidebar as you wish. There are 6 different layouts to use:
[columns]
[column width=”1/3″]
Right sidebar
[/column]
[column width=”1/3″]
Left sidebar
[/column]
[column width=”1/3″]
2 sidebars
[/column]
[column width=”1/3″]
2 right sidebars
[/column]
[column width=”1/3″]
2 left sidebars
[/column]
[column width=”1/3″]
No sidebars
[/column]
[/columns]