Free Ringtones for Windows Phone is an awesome application that lets you download thousands of ringtones for free on your mobile phone.
The catalog of Free Ringtones is amazing. They're optimized for ringtones already, and as a result last a maximum of 30 seconds. In the case of songs, Free Ringtones has already selected the best bit for a ringtone.
Free Ringtones lets you search by title or artist, and there's a preview, so you can listen before you download. We think this app is awesome, the only downside is that it doesn't offer any SMS alert tones - yet!