I went round and round with the googlers on dynamically generated URLs. Here's the deal:
1. Use as few parameters as possible (as stated above). Make sure the parameters are in the same order! Any difference in the URL is interpreted as a new page. That includes URLs with session ids that are encoded into the URL.
2. Always make sure that the URL to a given page is written IDENTICALLY!!! at every point in the site. As far as Adsense is concerned, these are three different URLs, and Adsense will waste days crawling all three of them as separate pages:
http://www.techetc.com/stuff.asp?Bnum=4
http://www.techetc.com/stuff.asp?bnum=4
http://www.techetc.com/Stuff.asp?Bnum=4
3. When you get your site up, go through and click through to every item on your site. In my case, I had about 550 different items (Bnum=1 to 550)! Otherwise, you will have customers clicking on the URL for the first time, and Adsense will display generic or humanitarian ads.
4. Don't forget to use Adsense's new alternate ad feature; that way, somebody you like will always get a link.
Now, if only I knew the four rules for getting people to CLICK ON ADSENSE ADS, I'd really know something!