With regard to the interest in glass buttons... I am not an expert, but have been collecting for quite a while, and also have quite a few reference books. I inherited a collection of buttons from my other grandmother (not the one who had the cool cordial glasses!) and at first learned much of what I know from books and Ebay. Actually Ebay isn't a bad place to start just to browse all the different types .... just remember some people don't know so much when they are posting and describing, but there are many experts there too. It's fun just to browse the button section, under collectibles and then vintage sewing. Often there are lots of good pictures.
I might be able to answer specific questions or steer someone to learn more, but Glass Buttons is a VERY broad topic. Paperweight buttons are very interesting, comtemporary ones are usually studio buttons made for collectors but some older ones were made to be used. Many victorian buttons are made of molded black glass. There are also "victorian jewels", which are often very ornate. I enjoy some of the "common" buttons such as the art-deco style glass buttons which were solid colors often with gold or silver paint accents that came in many different shapes. Many of the Czech glass buttons hit the mass market after the war, and are being reproduced today. Some of the differnt types are called "Aurora Borealis" (iridescent) and "Moonglow". Pre-early 1900's buttons would be considered "Old Glass" (vs. "modern") these were often molded, and some types are "lacy glass" "raidants" and "paperweights".
I am not aware of a discussion board like this for buttons, although I think there probably is one. Here is a link to a site with some good examples of glass buttons, and specifics for classifications of the National Button Society (yes... they have competitions and annual shows and it's quite a big thing! :-)
http://www.vintagebuttons.net/glassbuttons.htmlHolly