Alternate Widget Sets is a good page for groups of widgets, or widget tools, available as packages/extensions on the internet.
What is a widget? A widget, in my mind, is a piece of software designed to allow a developer to organize a method of communicating with the user. It may be used for visual display of info, visual input of info, or invisibly organizing other widgets.
- tklib is a hoped for module of the http://tcllib.sf.net/ project which will permit users to contribute script based Tk procedures and widgets for easy distribution.
- A little date chooser is a widget for selecting a day/month/year
- An i15d date chooser is a next generation of the previous chooser, specifying a number of languages for the days of the week and month names.
- A little hypertext system is just that - a way to show and allow following of links
- Bryan Oakley's combobox can be found here 
- Donal Fellows combobox source is here 
- Bryan Oakley's multicolumn listbox is here 
- Another hypertext widget is tkhtml.
- http://sourceforge.net/projects/tktable provides a widget with rows and column display. Think framework on which you can display tabular data or even build up to a spreadsheet.
- A scrolled frame
- Agentk Widgets
See Widgets in the initial Tk package on this wiki. Too bad someone hasn't done something similar for the other packages mentioned here and elsewhere.
What about things like these text widget techniques? Do these seem relevant here?
- Text Widget Example
- Text Widget Newline Wrapping
- Text Widget Syntax Highlighting
- Text widget undo/redo
- Multi-column display in text widget
- Read-only text widget
- A change-sensitive text widget
- URL behaviour in a text widget
- multi scrolling
- Show me all!
And these entry widget techniques?
And finally these other items.
- Keyboard widget
- Overloading widgets
- Tailing widget
- Scrolling widgets without a text or canvas wrapper
- Adding User Data to Widgets the Megawidget Way
- Paning widgets
- Overloading a widget command
- Measurement widget with units conversion
- Dial widget
- How does one change the font in the wish widgets - the option database is one solution!
- contour plot
- Portable keystate
- Serializing a widget
- Minimal scrolling canvas
- Complex scrolling
- Accessible widgets
[[If any of the above needs moved around, feel free to organize as most useful.]]
See also Arts and Crafts of Tcl-Tk Programming