Speech Preferences Click to see a larger image

I replied that text-to-speech is built into OS X and can be used in almost every application.

Here's how to get the Mac to read your text:

1. Select the text that you want to be read aloud.
2. In the Edit menu on the Menu Bar, select Speech > Start Speaking.

The default voice in the US is Alex, but there are many more to try out. There are a few other built-in US voices to choose from. I happen to like "Vicky."

There is also a list of "novelty" voices like "Deranged and Zarvox. They are fun to play with but they quickly get annoying.

In Lion, you can also choose from a huge library of voices that speak other various English accents as well as voices that will speak in many of the other major languages of the world. To save space in your hard drive, these voices are not installed as a part of Lion. If you choose one of these voices it is downloaded on the spot.

Hint: Having your text read aloud can be a good proofreading tool.

UPDATE: When I mentioned voices available in other dialects and languages, I gave the impression to some people that these voices would translate text as well as speak it. This isn't the case. Each of the voices "know how" to speak in their respective languages. Alex, for example, reads American English well but when I had him try to read some French poetry, it was a disaster. Alex pronounces French words using English pronunciations. I downloaded Sebastien which is a French voice and he did a pretty good job with the French poem. I gave Sebastien a shot at a paragraph in English and he mangled it beyond all recognition. The language specific voices in Lion are only useful if you have text in that language that you want to read aloud.

If you want a tool to translate text, check out Google Translate. I wouldn't say it does great translations but it is usually good enough to get the point across.