The popup blocker is an excellent function for those people who know when and why to use it, but for most people it prevents them from viewing important information as well as advertising shat. (IE it will, as mentioned stop an Amazon or Euroffice with popup 'offers' as well as the' internet washer' ad.)
I stopped using popups for 'compulsary' functions long ago, because it is tiresom telling people to disable their 'anti popup' functions before they used the site, (most people don't bother to email support, they give up).
I think the best way forward is to, as mentioned, introduce any offers as the customers progresses through the sale. It is quite logical and normal to say read an offer of 10% off or £3 free from your first order and not 'action' that 'deal' until further normal interaction with the website occours. (why popup a 10% off deal and ask the customer to add it to their cart, before they have even chosen to shop?). In my view it would be easier to introduce it either in the wording of the advertising that brought that lead or use a big flashy button in the first paragraph of you page

Then add it to the order automatically when the customer starts to shop.
And there are always layers or i F r a m e s to use these days as well.
The rest of the google bar I find is very usefull, with a blog button not far away. Its also adisable to 'pagerank' your own site by clicking the smiley face. And pagerank any page with a ligit link back to your site

- The same goes with the alexa toolbar - if you have a new url or website you can use the alexa toolbar to 'submit' your website alongside any links that you feel are relative. Do this correctlt and you will move up the pagerank (hyperthetically, never tried it, was on the DGM2 website somewhere - Thanks)
Barry
www.the-jigsaw.co.uk