I've evaluated two new pieces of software today. One had a quirky interface, bad help and was difficult to figure out. The other was Mars Edit 3. I shall be licensing soon I think.
On my first post I was pleased to see how easy most tasks were - except one. When I tag my posts in the Wordpress backend, I can pick from a list of my most common tags. I use this every time to ensure there are meaningful tags that refer to more than one article, rather than tags unique to each article.
Any chance Mars could fetch that list (or even a complete list)?
Another option might be "recent tags", seeing as you've already fetched a bunch of recent articles and their tags are already shown.