The Humanscale switch mouse works well for a hybrid vertical / standard mouse.

http://www.humanscale.com/products/product_detail.cfm?group=...

I use one daily and really like it, although its made of cheap plastic. The $99 list price is pushing it, you can probably find one on ebay for ~$30. I got mine for free at the Humanscale showroom when I went to look at their chairs.