I wasn't using them until recently, but I saw a rise in my search listings afterwards. But that was in Yahoo and not Google (only because Google doesn't show my site in the serps, at least not yet)
I don't really have any heading on my page so can't really use them. I don't like them anyway as you can't control the text size. I don't think so anyway
[url=http://www.80smusicforum.com/]80s Music Forum & News[/url]
If you have some good headline then to should use h1 tag to highlight it from the rest of the text. Try to use some of your keywords in it, this will benefit you though not for Google but for others : no harm.
<H_> tags are used to give a useful hint on the important parts of a web page. Having your keywords there (if those are really included in the content) it will going to be good for your site's visitors and the SE spiders