Dop-IOS lets you download and install any IOS from Nintendo servers. You can also apply the trucha bug to them.

Changelog:
Version 8
* Updated to all 4.2 new IOS.
* Gamecube pad support.
Version 7
* Fixed 'IOS62' bug.
* Added IOS56.
* Added short descriptions to IOS selection.
Version 6
* Added support for IOS57.
* Cleaner code.
Version 5
* Fixed a bug introduced in v3 that let you install stub IOSes.