Personally, I've been trekking all over Outland attempting to complete every last straggler quest while the rewards are still worth bonus gold. Once the expansion hits, these quests will reward experience again, and therefore, less moolah.
In fact, if you look at your rewards in your quest log, you'll notice the numbers have already been reduced in anticipation, although you are still given the full amount upon hand-in.
It occurs to me though that I might be shooting myself in the foot. How stable and playable do you think Northrend and the new Death Knight starting zone will be right off the bat? Some people are planning on spending the first few days leveling past 70 in Outland just to avoid the crowds, lag and frustration.
Are you hurrying to finish quests before the expansion, or are you planning to lay low in Outland for the first few days of post-expansion bustle?