About the same as
<meta name="google" content="dear google, please list me at number one">
In other words nothing

Search engines decide for themselves how often
to visit your site from how often your content changes and how often they
find new pages, google especially uses the "If-Modified-Since" header which
your server should send - ask your host. To keep search engines coming back
make sure your content changes regularly. I'm fairly certain there's a
direct link between how often your content changes and your ranking - can't
prove it but I wouldn't bet against it either