www.digmypics.com where they scanned my many slides at 2000 dpi, burned them to DVDs (as full res tifs and medium res jpgs), archived them, printed out a thumbnail album, and mailed them back in less then a month for only $550! After having the digital results in my hot little hands for a couple of hours, I am convinced that it was money well spent.
If you are an aging geologist with a rich photographic slide archive, sit back and think about the likelihood that you are ever going to delve very deeply into it again. My guess is that you may never see most of them again. Have them scanned and you will be able to peruse every single one of them, otherwise they will just get more deeply buried, more disorganized, and ultimately fade away. Take a few minutes to think it over...once you have faded away, no one wants to go through your slide collection if it is not digital (at least probably not).