A note about the tag count. Hovering the mouse over a tag will reveal a tag count message like '2 things tagged with ...'. This count (number) will vary depending on where the tag is being displayed at the time.
The 'More tags' page (and the tags block) can display several different selections of tags - for instance 'all tags' or 'my tags'. The count displayed for a tag under 'all tags' may be different to the count for the same tag displayed under the 'my tags' or one of the other selections. This is because when 'all tags' is showing, all tags for courses, blogs and user profiles are displayed and counted. Where as when 'my tags' is showing, only your own tags for courses you have tagged are displayed and counted. So the count could be quite different for one tag under different sections.
Of course the size of the tag is also a clue to the count. The bigger the font size for the tag the more popular the tag is.
In fact it is easy to re-order the tags displayed by popularity, using the link provided. And the tags may be re-ordered alphabetically or in date of creation order as well. Try it.