Interesting input formats or filters or whatever Drupal calls them

htmLawed

http://drupal.org/project/htmLawed
Saves the world and brews your coffee.

The highly-customizable htmLawed filter can be used to make text with HTML more secure, and HTML standards- and admin. policy-compliant. It can auto-correct and beautify HTML markup and restrict HTML elements (tags), attributes, and URL protocols in the input. It also balances tags and checks for proper nesting of the HTML elements. Furthermore, it can transform deprecated tags and attributes, check and convert character entities (e.g., from hexadecimal to decimal type), obfuscate email addresses as an anti-spam measure, etc.

External links filter

http://drupal.org/project/elf
by m3avrck - simple filter that adds a CSS class to all external and mailto links. There is a configurable option to include a CSS file that adds different icons for external and mailto links as well

FlexiFilter

build your own:
http://drupal.org/project/flexifilter

Mobile Codes

http://drupal.org/project/mobile_codes

Mobile Codes generates Datamatrix or QR Code mobile barcodes that can be read by many camera phones.

This one I'd rather have for CCK fields and such rather than as an input format, personally, but– awesome! Add this to the printer-friendly version of pages for a link back to the page, could be one great use.

XML Content

http://drupal.org/project/xmlcontent

XML Content is an XML entry, XSL transformation, and XML validation module that leverages PHP xml and xsl support, and the drupal output filter system.

For SCF.

Resolution