A proposal for tag hierarchy on SO
Since so many thousands of tags and topics exist, it would be really useful to visually browse through tags by organizing them into a hierarchy, or hierarchical map. This drill-down map would make it easier to find the tag/subtopic you want or just generally browse within the topics you're interested in.
So we could nest all "visual-studio-2008" and "visual-studio-2003" tags into "visual-studio", which would be under "dev-tools". Something like how Wikipedia's categories have sub-categories.