Can I manually tag entries?

Yes. If you have previously manually tagged entries on your blog then Jiglu should pick them up and use them alongside your automatically-generated tags. (It looks on your pages for <a> tags with an attribute of rel="tag".)

You can also manually tag pages in Jiglu itself - log on to the system and select the 'Pages' tab at the top of the page. Then choose the edit button next to a page and you can manually assign tags.