It would be nice to add a couple queries to the harvest feature.

When you add a tag, it’d be nice to have that tag go back to the start of your blog. For instance, I just put this module in. my blog has over 2000 entries in it. But the tags start last week. So nothing is tagged previously. It would be nice to add a check box to use the suggestion type feature and add the tag to previous entries. It could be a query that presents a list of topics you’re about to apply it to, or a simple number. eg: “Applying this tag to your previous entries will apply [532] blog entries with [tag].

the problem I see here is the load the database server might present, but in most blogs I would imagine it’d be short enough to not create a load issue. Maybe it could be a maintenance feature that is in the tags module section but not the tab on the publish page.