Rather than change visibility for individual blocks, you can group them together and assign complex visibility settings to all of them. Module page promotes it as a simpler alternative to Panels.
Provides a block with a tag cloud of chosen taxonomy term. Works but a bit buggy, e.g. UI taxonomy setting reverts to 'tags'. Requires clearing the cache to update (including changing any settings). Choice of numbers after each tag to indicate quality, or 'wordcloud' style with varying sizes (will need you to modify your CSS to add some spacing between words).