I always found the 20-way drop down with language pairs ("English to French, Portuguese to English" and so on) on web translation sites annoying. The proper thing for these services to do is to detect the language of the page you want to translate on their own and just show it in english already - an expert interface could be a button away, but simple things ("this page to English") should be simple.
I've made a bookmarklet (and a perl script) that does exactly this. It loads a webpage, tries to guess the language used, if Google translate supports it it is then translated and you're done.

In english

Drag it to your toolbar. The usual Javascript bookmarklet security caveats apply. The code will know about pages you load, and clicking on the link will let me send you anywhere. But I don't.
Don't abuse it please, or I'll have to take it down.

The underlying language categorizer is TextCat. This service works no better than TextCat does.

[UPDATE: This actually works directly on Google]