Cascada

Boy... meets Girl...

—Miracle's first line

Cascada is a European Eurodance/Trance group from Germany. It is made up of the lead singer, Natalie Horler, and two DJs, DJ Manian and DJ Yanou. They are most famous for their covers of "Everytime We Touch" by Maggie Rielly and "What Hurts the Most" by ~~Rascal Flatts~~ Jo O'Meara, as well as origional compositions such as "Evacuate the Dancefloor", which went near straight up to No. 1 on the charts in the United Kingdom.

Discography:

Everytime We Touch (2006)
Perfect Day (2007/8)
Evacuate the Dancefloor (2009)
Original Me (2011)

Cascada provides examples of the following tropes:

Break Up Song - "Miracle".
The Cover Changes the Gender - Most notably for "What Hurts the Most" and "Truly Madly Deeply". And it works.
Cover Version - although their first two albums consisted mostly of original songs (and Evacuate the Dancefloor, not counting Faded on the European release, and Original Me had no covers on them), their most popular hits are covers.
In Da Club - Ditto for the video of "Evacuate the Dancefloor".
Lighter and Fluffier - Compared to Everytime We Touch, Perfect Day is much lighter in style.
Lyrical Dissonance - In Natalie's cover of "Just Like a Pill".
New Sound Album - Some of the songs on Evacuate the Dancefloor are in R&B/electropop style.
No Export for You - Four songs were left off the American release of Perfect Day, two of them covers ("Just Like a Pill" by P!nk and "Sk8r Boi" by Avril Lavigne) and two of them remakes of older songs from pre-Cascada made by Nat and Manian. The America release had "Faded" and "Holiday", which were not released in the United Kingdom, but "Faded" ended up on Evacuate the Dancefloor.
Sound Effect Bleep - Heard in "Fever", where a bleep-like background noise that's there for most of the song turns louder than it should on a certain line...