OKay, what is the best what to redirect to the main page of a blog (or even a particular page) when people put in weird words or whatever at the end of the domain?

For example, looking at stats of one blog, scads of people (for whatever reason) are coming to my blog using:
blogname.com/content/images/hernude.jpg (must have on one blog about 500 hits using different names).
Or:
blogname.com/submit.php, blogname.com/contact.php and so forth.

I want it so anyone putting any invalid words after blogname.com will instead go straight to the main page.

Thank you.