Unfortunately, the Olympus e510 does not have the optional extra hand battery grip which for many folks including myself is the only thing that prevents us from buying the impressive mid range priced DSLR (Digital Single Reflex Lens) camera. Nonetheless, there are third party extra hand battery grip as in the below comment. Top of the line DSLR camera models that have their original brand optional extra hand battery grip include the Olympus E3, Sony A700, Canon 40D, & last but not least, the Nikon D300. All of the DSLR mentioned above cost over $1000.
Just as an FYI, there is actually an aftermarket Battery Grip for the E-510.
http://www.gadgetinfinity.com/product.php?productid=16832
Fascinating.
Thanks for the useful link.