I just love the idea of using juxtaposition in interior design. There's a fine line, however, between creating an intriguing tension by using opposing styles or colors, versus creating a look that is mismatched and irrelevant.
Ideally, opposing elements should highlight one another, while retaining their own independent value. Here are some examples that I think work beautifully...
Juxtaposition - love it or leave it (or leave it to the experts)?