Janar

With this plugin you can add extra HTML or just plain text when posting a new page or post. That content will be displayed in sidebar widget. It is tested from WP 2.6 to 3.0.1.

ax-sidebar

With this plugin you can add extra HTML or just plain text when posting a new page or post. That content will be displayed in sidebar widget.

janekniefeldt

Use this plugin to create your own widgets, duplicate existing widgets and arrange them in a sidebar or anywhere else. 
Thanks to filter definitions you can decide whether the widget should be displayed or not for specific pages or page-types.
This plugin does not work with WordPress 2.7.1 and below. 
If you are using WordPress 2.2 – 2.7.x please use Release 1.9.1 of this plugin.
The following features have been implemented:
<ul>
<li>define own widgets with php and/or html code </li>
<li>decide where your widget should be displayed (e.g. archive-page only)</li>
<li>define your own filters through plugin configuration</li>
<li>widget-titles that fit into your theme can be defined and changed comfortable as well</li>
<li>Debug-mode for code review</li>
<li>apply_filter-functionality can be activated within CustomWidgets </li>
<li>widgets are also available through custom tags such as <!–MyWidget–> 
and can be used outside of the sidebar as well</li>
<li>duplicate/copy existing widgets (beta feature)</li>
<li>deinstallation routine to remove all option entries created by the plugin </li>
<li>Backup routine for widget- and plugin-configuration</li>
</ul>

My Custom Widgets

Plugin to create your own custom widgets.

ax-sidebar vs My Custom Widgets