Get a taxi to the city centre mall (10 minutes max), and jump on the Big Bus Tour. It takes around 2 hours and you'll see all the sights (Burj-al-Arab, Burj Khalifa etc.). The bus leaves from when the taxi drops you.

Alternatively, head to Le Meridien Village for a few drinks and a meal. There are a huge number of restaurants and bars. It's right across the road from T1, or a short taxi ride from T3.

Cheers,
Rick