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

Changes:

It seems that ES_Identify patch can be buggy in other IOS than 36. So now Dop-IOS is able to apply this patch only on IOS36.
SD files now are stored on sd:/00000001 and they can be used in other applications.
Now Dop-IOS v4 shows your installed IOS versions!

http://wiibrew.org/wiki/Dop-IOS