I'm about at my wit's end. My boss constantly lets me down by promising to deliver things I need in order to do my job, and then not delivering. He's one of 2 owners of the company. He works at a different office than the one I work at. He tells me he's put stuff in the mail for me, and then 2 weeks later when it hasn't arrived and I follow up with him, he tells me "oops, never sent it", and then another 2 weeks later he still hasn't done it. He tells me he's going to follow up with a customer/client/vendor and then doesn't do it. It's causing my work product to suffer because I can't deliver on the commitments I make, it's causing me to look bad to my team, to our clients and vendors, and to the other owner. I'm constantly apologizing to everyone for not delivering on my commitments. I don't throw him under the bus because I don't feel that's professionally appropriate. I'm losing sleep over it. I've listened to the "Managing your Boss" podcast and based on how I've seen him accept feedback from other subordinates in the past (very poorly) I know I can't give him feedback on his behaviour even if it was just to TELL me he's not going to give me what I need.
I care about doing a good job, I take commitments that I make very seriously, I despise making excuses, I love the company I work for. I don't know what to do, any help or advice would be much appreciated.

Owning the inputs
First:
It's good that you don't throw him under the bus - that's very professional of you; kudos.
Now:
How can you become less dependent on him? Can you follow up with the vendor or the client, instead of him doing it? Can you send the UPS folks to pick up the package from his office? Stop relying on him. As a manager, I love it when my directs keep me out of the critical path!
Take stuff off his plate. He's undoubtedly busy, likely distracted, and often hit with higher priority items. That's just reality. So take the little stuff off his to-do list, and you'll be more effective.
John Hack
Empower your boss
BLUF: Empower your boss by playing to his strengths.
John is right and I can sympathize with you. My boss is a high I and sometimes forgets to follow up on things.
The first step is, don't let it bother you so much. Your boss has strengths, but if you are upset at him, they will be harder to see.
The next step is empower your boss. For example, my boss can develop strategic initiatives and can develop relationships with people pretty easily. He understands how our group needs to provide services to our organization. So, I help him do it. If we are in a meeting and he promises to send something, I interject and offer to send it. If it's something I don't have, I find out where he got the information and I get it from his source so I can send it. If he says he will follow up with someone, I follow up with them (I just make sure I understand what his goal is and what his position is). Then I follow up with my boss and let him know what happened. My goal is to ensure he walks away with no deliverables.
The best part of empowering your boss is that you will end up getting affirming feedback. "You take ownership." "You get things done." "If I really need something done, I give it to you."
You and your boss don't need to work the same way to work well together.
Hope this helps.
Chris
thanks
Thank you both for weighing in.
I've actually spent quite a bit of time minimizing my exposure to his lack of follow-through already but there are probably other things I can do as well. He's reacted less than favourably in the past when I've taken initiative to do things he's committed to doing (following up for example) despite positive results.
Calpron, your comment to remember that he has strengths too was very helpful. The fact that I couldn't think of any for several minutes told me that I've lost perspective on the issue. He does have strengths and my time is better spent trying to take advantage of those strengths than focusing on how his weakeness cause problems for me.
Again, thank you both. I really appreciate it.
M