ちりも積もれば山となる

Excite翻訳: The many a little makes a mickle.
＠nifty翻訳: Many a little makes a mickle
Babel Fish: If it accumulates also the dust, it becomes the mountain
Google翻訳: The dust and mountains積MORE
Yahoo!翻訳: Drop by drop the tub is filled
OCN翻訳: When it's also full of dust, it'll be a mountain.
Windows Live Translator: Becomes Mount 積もれば also dust

Summary:
Excite, @nifty, and Yahoo! have fixed expressions.

Reverse Translation)
Excite翻訳: 少しがaたくさんにする多く。
＠nifty翻訳: 塵も積もれば山となる
Babel Fish: 塵をまた集めれば、それは山になる
Google翻訳: ほこりや山詳細积
Yahoo!翻訳: 一滴ずつ、桶は満たされます
OCN翻訳: またそれが塵でいっぱいの時には、それは山です。
Windows Live Translator: 積もればも埃マウントになります。

Summary:
@nifty handles the expression as a fixed saying while Yahoo! produces a natural expression.