tktable is a full-featured 2D table widget for Tk.
Some of its features include:
* multi-line cells
* support for embedded windows
* row & column spanning
* variable width columns / height rows (interactively resizable)
* row and column titles
* multiple data sources 
* supports standard Tk reliefs, fonts, colors, etc.
* x/y scrollbar support
* 'tag' styles per row, column or cell to change visual appearance
* in-cell editing - returns value back to data source
* support for disabled (read-only) tables or cells (via tags)
* multiple selection modes, with "active" cell
* multiple drawing modes to get optimal performance for larger tables
* optional 'flashes' when things update
* cell validation support
* Works everywhere Tk does

Possible conflict:
The BLT package (tclblt) also has a command named "table". It's
possible to avoid such conflict by renaming one command or another.