I'm an administrative assistant who has begun to manage projects. I asked for a promotion but it's slow coming due to budgetary constraints. Do I wait for the promotion? Do I accept more responsibility or turn it down until I'm promoted?

Definitely don't turn down additional responsibilities just because you're not getting the promotion. That would just be cutting off your nose to spite your face because the new projects will teach you a lot and make you more valuable - both to your current employer and to any future employers.

Never, never, never turn down the chance to take on more responsibilities - I can't stress that enough. And that goes double for economic downtimes, because the more valuable you are to your company, the less likely you are to lose your job during any lay-offs. (Trust me - as an HR exec, I had the unhappy task of organizing several lay-offs and it always comes down to who is expendable - the more you are doing, the safer you will be).

That said, I'm not advocating that you let people walk all over you. If you feel your current situation is untenable long-term, you can start to quietly explore other options. But you will be doing so with the additional experience and knowledge that these new responsibilities have given you. If and when a great opportunity comes up, you can decide whether you want to stay or leave. Until then, you don't have to make any decisions - just keep as many options open as you can. And the first step in doing that is accepting as many new responsibilities as they will give you.