Here are my suggestions:
First, Heward's Handy Haversack (already on your list).
Next, one or two of
every useful small item in the Equipment chapter. Rope, tindertwigs, oil, holy water, pitons, mirror, chalk, sewing needle, fishhook, etc. If there's room in your magic item budget, get some magic stuff that might come in handy, e.g. Quaal's feather tokens, golembane scarab.
It's great to be able to pull something out of your pack at the right moment. A bunch of golems and only one fighter can get through their DR? "Just a sec, I've got a golembane scarab right here." My DM wasn't thrilled.
Speaking of DR, if you don't want to be left out of some fights entirely, get a couple of extra weapons that can hit various DR creatures, e.g. a cold iron rapier and a silver light mace. Plus silver and cold iron arrows if you use a bow. (And I do recommend getting a shortbow, for those times when you don't want to bring your measly collection of hit points too close to the enemy.)
With Use Magic Device, a wand of Cure Light Wounds is a good buy, and it could be a party-saver if the cleric goes down.
I like Slippers of Spider Climbing, but there are umpteen other magic items that are also useful.
I'd choose a mithral chain shirt instead of glamered armor. I can't think of any situations my character has faced where glamered armor would have helped, but YMMV.