Deleting the architectures in my early 2008 Macbook Pro running Snow Leopard messed up a few programs. CS5, MS Office and Pages stopped working. Many icons also went missing.
I made a back up, so it's all gravy baby.

@developer

Hello, could you make it possible to have a downloadable database or back-up of the language files? (to restore them).
Or if there's already a special way to do that I'd love to know.

I just used Monolingual for the first time, and it has made it impossible to open Word files from earlier versions. How do I fix this? This is a huge problem since Word is the main software I use.

Yesterday I ran Monolingual 1.4.5 on my MacBook Pro (OS X 10.6.6) with the iOS DevKit and quite a few 3rd party apps installed. I chose to have it only remove unneeded languages and leave "Input Menu" and "Architectures" alone.

The process took about one hour to complete and recovered 2.2 GiB on my root partition. I am running low on space, so this result was quite welcome, and it's good to know that I could at any time save more space by stripping the binaries, too.

So I'd say Monolingual is a great tool which I can recommend.

BUT it's a dangerous thing, too. At my first attempt I almost shot myself in the foot by checking off the wrong language. The list of languages is very long and it is crucial that you look very closely to avoid making mistakes here. I only just happened to spot my error early enough to stop the process before it had actually removed something... Phew!

Pretty much all the complaints I've read in the comments can be explained by user error . . .

Worked well for awhile but then after a few runs in a months time iTunes no longer would open and I was forced to reinstall OS X. Best advice I can give to someone using programs like this is to always back up your files!

Under Snow Leopard this version of Monolingual does something to its preferences file that causes the application to crash after a number of runs. deleting net.sourceforge.Monolingual.plist and then resetting personal preferences fixes things for awhile, until next time. I just tried locking the preferences to see if I get better mileage. Time will tell.

I incidentally deleted the english(u.s) yesterday ,and now I can't type anymore, keyboard disabled. anyway I can go through it?

Monolingual 1.3.8 will break Mail.app on Leopard and possibly other code signed applications.

I can manage to consistently break Mail.app and cause it to popup the password window. It will then never remember the password, attempt to store or attempt to retrieve it from the keychain *if the Application code signature is invalid*.

In testing I've tried removing many things from Mail.app such as language files, compressing images, removing redundant unnecessary files and stripping the redundant PowerPC binary and various other things from the bundle. None of this seems to damage Mail.app's code signature.

How do you break Mail.app you ask?

By stripping the debug symbols from Mail.app using one of many app trimming applications such as Monolingual. Since Mac OS X 10.5 Leopard introduced Code Signing and Apple Mail is code signed my guess is that because the bundle is changed and the code signature is then broken and invalid Apple Mail is then treated as an untrusted application and is refused access to the keychain by SecurityServer.

According to
http://developer.apple.com/releasenotes/Security/RN-CodeSigning/index.html
applications should trigger a popup confirmation to allow the Application to update the keychain but it appears that Mail.app does not do this and SecurityServer suppresses the dialog as the code signature is invalid.
I have filed as Apple Bug ID #5734181

Opening Console.app and checking secure.log shows many entries from SecurityServer to advise:
Feb 10 23:04:02 macbookpro com.apple.SecurityServer[20]: suppressing keychain prompt for invalidly signed client /Applications/Mail.app(7514)
Feb 10 23:04:32: --- last message repeated 16 times ---

If you are getting these messages, this wll mean you may need to restore from a backup version of Mail.app from storage, time machine or another computer. If you re-install the app from the original 10.5 Installer CD you may also need to run the 10.5.1 installer and Security Update to ensure that Mail.app is up to date.


===================================
Technical Details for strip command
===================================
/usr/bin/strip: changes being made to the file will invalidate the code signature in: /private/tmp/Mail.app/Contents/MacOS/Mail

Stripping debug symbols.

#!/bin/zsh
#This shell code sample taken from Trimmit.app
[[ -n $sym ]]&&{
# strip debug symbols. "2>&1" means error messages to the standard out.
/usr/bin/strip -Sur Contents/MacOS/*(*) 2>&1
/usr/bin/strip -Sx **/*.dylib(N) **/*.framework/**/*(*N) 2>/dev/null
echo "== Stripping debug symbols."

I just ran this program and I didn't see that Intel 64bit was checked to be removed, will that cause any probelms on my mac book, i just bought it today so I want to know if i should reinstall before I put too much on it?

thanks