情けは人のためならず

Excite翻訳: To help others is to help yourself.
@nifty翻訳: Do good: thou doest it for thyself
Babel Fish: Mercy does not become, for the person
Google翻訳: Mercy is not for people
Yahoo!翻訳: The sympathy does not become it for a person
OCN翻訳: Mercy won't be for a person.
Windows Live Translator: Mercy did not become for people

Summary:
Excite and @nifty show the meaning embedded in the Japanese saying.

Reverse Translation)
Excite翻訳: 情けは人のためならず。
@nifty翻訳: 良いことをしてください:汝、doest、それ、自分のために
Babel Fish: 慈悲は人のために、ならない
Google翻訳: 慈悲の人々のためではない
Yahoo!翻訳: 同情は、人のためのそれになりません
OCN翻訳: 慈悲は人に向きません。
Windows Live Translator: 千手観音にとってならず

Summary:
It seems that Excite has the fixed combination in its dictionary.
Babel Fish's is a typical wrong understanding recently made in Japan.