I noticed that there are some tags that are the same as an existing tag but with a version number. I would think that this kind of specificity isn't necessary here at Programmers. Version information can be more accurately expressed in the question title or the question itself if it is relevant. Since we focus on conceptual questions about software development, I can't imagine specific version information is helpful when tagging.
On Stack Oveflow I think these type of tags make sense because questions can be tagged with both the general and specific tag due to volume and the direct nature of many questions. That is, having tags with specific versions is useful and complementary to the un-versioned tags.
So, with that in mind, I gathered a list of tags that might be worth taking a look at. However, I do think there are special cases and have grouped some of them separately. Feel free to contest any of these, as I am not 100% sure about a few of them. If this is just stupid, let me know and I'll walk away. It just didn't make sense when I saw a couple of these tags today.
- css (104) and css3 (5)
- html (155) and html5 (78)
- python (368) and python-3.x (3)
- visual-studio (83), visual-studio-2008 (3), and visual-studio-2010 (77)
- windows (146) , windows-7 (8), and windows-8 (18)
Special Cases (as in, they should be separate)
- c++, c++0x, and c++11 - The language and its specifications
- c and c99 - The language and one of its specifications
- db and db2 - One is a synonym for database, the other is a database
- struts and struts2 - These are entirely different frameworks, similar in name only.
- visual-basic and visual-basic-6 (per Yannis' answer)