Last.fm free music player

Last.fm free music player is a free music player for Google Chrome with Last.fm integration, it changes the play buttons on Last.fm-pages to play music from VK.com.

How does it work?
There's a little site called vk.com. That's where the tracks are coming from.

Do I need a vk.com account to use the player?
Yep, and you have to be logged in. In order to register however you'll need a phone with SMS capability.

That's a Russian site, right?
Yes, in Soviet Russia, track scrobble you. Actually, it's like Facebook, with a dash of YouTube. It's not one of those "Psst - hey, Buddy. Wanna download some MP3's?" sites. 195 million people and counting use this site. Wikipedia

But Last.fm says "We think the site you're about to visit is untrustworthy or spam..."
Well, McAfee SiteAdvisor seems to think it's OK. There have been phishing scams aimed at users of that site, but the site itself is as legitimate as the above mentioned sites.

OK, so far, so good. Now this Chrome extension is telling me that it needs to access my private data on all websites. What's that about?
It does not access your private data. Chrome shows the warning for all extensions that access browser tabs even if they do not access any private data. See this discussion that explains it.