Remixes are the lifeblood of music for a lot of people, including some of us here. Rihanna's songs are often incredible when mixed--try Rockstar 101 vs. Come And Get It (Rihanna vs. Selena Gomez), because even you are only lukewarm on both of their musical styles, the combination is great. Another great mix is Rude Boy vs. Baby One More Time (Rihanna vs. Britney Spears).
Also try What Goes Around In Rehab (Rihanna vs Justin Timberlake) and the interesting Love The Way You Roar [Katy Perry vs Rihanna].
Some other great mashups are I Am The Best Freak [2NE1 vs. Enrique Iglesias & Pitull] and the more Korean pop oriented/Kpop piece Electric Lucifer [f(x) vs. SHINee].
If you like slower, more almost-ambient yet rhythmic music, try Bahramji or the great, mystical Klaus Schulze [like his track 'Freeze'], the somber Baths or more peppy Octo Octa.