It's a bit strange to consider that my post about playing a new character is only about 2 weeks old. I've already worked up my Tempest of Set to level 48.
It's funny reading Krisroe's post below about running out of quests, because I'm in exactly the same position. The Fields of the Dead quests are running out quickly, and I'm forced to do some orange/red quests above my level, too; my character is powerful so it's not too bad, but I haven't been upgrading my equipment very throughly. Unfortunately for both of us, it seems that most of the quest content runs out at about this level, so we'll both be stuck.
One nice thing about AoC is that you can still get a fair amount of experience from doing older "gray" quests. I've done almost every solo quest so far, and have gotten a lot of experience. But, even that doesn't help if I'm running out of quests to do.
One thing that's hurting me currently is that one type of quest seems to be broken. I can get some quests from signposts in the Fields of the Dead, but when I complete the quest it disappears instead of letting me turn them in. So, no big boost in xp from finishing the quests. I don't know if the quests are bugged for everyone, or if I accidentally broke something when I re-read a sign just as I was about to turn in one of those quests.
Anyway, I might go back and give my Bear Shaman a bit of love as things are slowing down for my Tempest of Set. I'm not eager to just grind with the character to see the highest levels.