I know adwords does not allow a landing page to have entry or exit pops, but does anyone know what the consensus is on JavaScript alerts or DHTML "pops"?
I can't guarantee you that I'm 100% right, but I'd say: Javascript: Nope, as it actually a small but new window which needs to be closed by the user (real pop-up) Basic floating Popups: yes, as it's just part of the webpage content, which doesn't require extra user interaction.
floating DHTML window over the landing page is ok. You can see this on most salesletter-type sites, which are usually landing pages for Adwords ads.