The best way to do this is run the basic information that changes from a central database (or flat files) and use PHP or Perl to create the pages. I do that with my sites so one update covers everything. However, if yours are HTML then….
…take a look at http://www.casinofeed.info which i’ve put together for exactly this type of scenario. Its in its infancy but it will mean all the bonuses and promos from all the casinos you represent (as they come onboard) will be served to your site in “real-time” with javascript so you actually won’t need to update your websites on that front if you prefer less hassle 
We Beta tested it with data from Referback, 32Red and VPL and it went well, so in December we’re rolling it out to some live sites and starting to talk to other affiliate programs about it – so feel free to give it a try, the data is “Live” data – it’s real easy to put up and should make life easier – hopefully!!
I’d just ask you send me the URL if you do as I’m compiling a links page of example sites that are involved and a Press Release for January.
Hope that’s useful.
Cheers,
Simmo!
Hi
thanks for the info, I have taken a look at your feed and done a quick test on my site, seems to be working well at the moment http://www.microgaming-casino-reviews.info/component/option,com_newsfeeds/task,view/feedid,19/Itemid,47/