SoundGecko is a new web app that's essentially a text-to-speech transcription service. Drop a URL into SoundGecko and it converts the article into speech. On top of that, it integrates with cloud services and an iPhone app.
By default, the simplest way to use SoundGecko is to have it send you an email with the file, but you can integrate it into Dropbox or Google Drive for immediate syncing. You can also use the iPhone app to directly sync articles you've converted, and there's also a Chrome extension that allows you to add articles on the fly.
As far as the voice is concerned, it's what you'd expect from a text-to-voice transcription. It's a little digital-sounding and takes some getting used to. Still, for a free way to create your own MP3s of articles and have them synced pretty much anywhere, SoundGecko works efficiently and simply. Currently, SoundGecko is free for unlimited use. If you travel a lot and want to hear your favourite articles, it's worth checking out.