Mixtapes are a great way to hear some of the hottest hip hop and R&B artists before they go mainstream, or to hear content their label doesn't want (often better). Mixtapes are often available for download on their websites or fine ones like this.

First up, we have "Heartbreak Drake Part 3" from one of my favorites
Drake; he has a nice flow that blends rapping and singing together. The production on his songs are always great. The highlights from this mixtape are "Say Something", "Material Girl" feat.
Colin Munroe, and "Darlin", but I'm sure you'll enjoy them all.
Heartbreak Drake Pt. 3 Drake

Cleverly named "Burn After Rolling" is from
Wiz Khalifia. Wiz is a Philly rapper whose creative techno-influenced songs have set him apart. "Burn.." features Wiz rapping over some popular songs from artists like
Beyonce and even
Drake to guys like
Empire of the Sun. The "Thrill" is one of my favorites along with "If I Was A Lame" and "One Way". This is by far one of the best mixtapes I've heard, there are so many good songs it was hard to choose just three to mention.
Burn After Rollin Wiz Khalifa