Z33K is a versatile open source tool for locating, streaming and downloading music.
The heart of the program is its "MP3 Search" tab. Enter an artist or title here, click "Search", and z33k will immediately check mp3skull, emp3world and other databases. A list of search hits quickly appears, and these can be played or downloaded in a click or two.
Not sure what to search for? Click the Charts tab and you're able to view the iTunes chart, the "World Top 100", or the best-selling songs in the US, UK, France, Germany, Italy, Spain and more. Double-click a song title in any of these and it's sent to the Search tab, where again you can be listening to it in just a few seconds.
A "Radios" tab gives you quick and easy access to a selection of internet radio stations. Just choose your preferred genre (Alternative, Classical, Electronic, Metal, Pop - 25 in total) and double-click a station to hear more. The selection can be a little limited - only two "Pop" stations, really?! - but overall there's still plenty to explore.
Elsewhere, there's a module to search for song lyrics, as well as a simple ID3 tagger.
And z33k even includes a YouTube downloader, which can search for whatever video you need, download it (in your preferred quality), even convert it to MP3. (The conversion isn't as polished as in some of the competition - it just launches an FFMPEG session, which you get to watch in a console window - but it works, and is a useful addition to the program.)