Some people like mashups, others find them annoying. Most of the time they are pretty simple with the DJ mixing two or three songs and it not sounding much different except for a change in lyrics. Enter Brenton Duvall, a DC-based mashup artist who makes the track better through making it a song with a few tracks mixed in as well as adding some beats and remixes.
Below are two of my favorites by him. If you enjoy these songs, check out his soundcloud page with around 13 tracks by him.
http://player.soundcloud.com/player.swf?url=http%3A%2F%2Fsoundcloud.com%2Fbrentonrules%2Fworld-tour-weezy-wale-dre&secret_url=false World Tour (Weezy, Wale, Dre) by BrentonRules
http://player.soundcloud.com/player.swf?url=http%3A%2F%2Fsoundcloud.com%2Fbeforethebigszach%2Fbrenton-duvall-ambien-sleepy-trip-lil-wayne-x-passion-pit&secret_url=false Brenton Duvall - Ambien (Sleepy Trip) (Lil Wayne x Passion Pit) by BeforeTheBigsZach