So, just don't show any posts on the main page. That's not a lot of work, really.
- In Settings - Formatting, set "Show at most" to 0 posts.
- Add a "Welcome" gadget, using an HTML / Text gadget. Or compose a "Welcome" gadget using Post Editor, if you want a really shiny static home page. You'll have a couple choices for positioning the new gadget.
- If you want your Welcome gadget to look like a "Welcome" post, you can position it just above the Blog Posts gadget, and have the sidebar(s) visible.
- If you want your Welcome gadget to look like a "welcome" header message,, you can position it just below the blog header, and have the sidebar(s) below it and not visible.
- Tweak the "Welcome" gadget, so it only displays on home page.
- Remove the Status Message code from the template, so your readers don't have to look at the "No posts were found which match your query" / "Showing posts with label" message (both messages are produced by the same code).
- Add a custom pages index, to index the pages and posts in this blog, and other blogs. You can have either true static pages - or you can have dynamic pages, using labels.
- You're done - check it out.
If you wish, look at my Static WebSite Test blog, and see how simple it is. Note that my example shows a linklist in the sidebar, with mostly links to other blogs. It's a separate task (no more complicated than this one) to create a menu bar for this blog, to index pages and posts in this blog.
(Update 2010/09): The "Show 0 posts" setting is still available, but may require a small amount of extra work.