Ask HN: How to do dynamic real-time adverts ?

I'd like to be able to run some adverts (this is from an advertisers perspective) using real-time content, so my ads would constantly update with new content. Is this at all possible ?

The two options I see are:

(1) Using Javascript or Flash adverts to pull content in on-the-fly.

(2) Serving a dynamically generated ad image from my own servers

This is for a relatively small operation so I'm looking at advertising via something the adwords rather than something like DoubleClick where you need a large advertising budget. I don't think Google will let me take either of the above approaches, but are there other ad networks that will ?

(or are there any other ways this could be done)