When there's a song you really want to listen to you generally want to find it pretty quickly. mPPP is a super simple search engine dedicated to finding songs for you to download. If you find one you like, it'll upload it directly to your Dropbox.
When you get to mPPP's (pronounced MP3, by the way) main and only page, you just search for what you want. It'll find music from various sources. Sometimes those sources will provide actual music files and other times they'll be YouTube videos, but mPPP will convert them automatically so, as far as you know, you're just getting an MP3 file.
If you have a Dropbox account, this search engine gets really interesting. You can simply click the Dropbox icon to log in and then click it again to send the song you're currently playing to your Dropbox. Alternatively, you can just download it.
While this works well once you get the hang of it, the interface is so simplistic that it's actually a little hard to understand at fist. The play button is a power symbol and the Dropbox button both logs you in and sends a file to your Dropbox — but only if a song is playing in the player that is collapsed at the bottom of the screen. All of that said, the search aspect is very simple and these Dropbox features are worth the hassle. It's very cool once you get it to work.