There’s a few mashup artists who have been around the whole decade. DJ Earworm is one of them. This track, “Stairway to Bootleg Heaven” was from back in 2004.
But it’s not all airy dance stuff. In 2005, Go Home Productions put out this rocking mix of “Back in Black” and “We Will Rock You”:
And for something completely different: Wax Audio’s presentation of “Stayin’ Alive In the Wall”: