You'd think Nintendo would make their own Wii-compatible browser for players with Wi-Fi access however that's not the case. Instead you have to spend 500 Nintendo Points which is a $5 investment in downloading the Wii Opera Browser.
Using the Wii remote you select characters with the on-screen keyboard which can be somewhat annoying to input websites or write messages. You can actually use a USB keyboard if you own one to plug into the Wii just for that convenience - but that's another expense.
Like a normal browser it allows you to add sites to your favorites. Yahoo and Google definitely work on the Wii browser, so you can check your email for instance or do web searches (although if you're using your Wii to go online, most likely you're already at home, so you might as well just use your home PC for a faster connection).
You can watch videos, find images, articles, and so on. Seems like an unnecessary expense to me. I really don't understand why we have to pay for this when its really not revolutionary. At least its not a monthly fee, you pay the $5 once and the browser is yours unless you somehow damage your Wii and lose it.
Update On Oct 01, 2009: At the time I wrote this review, the browser still requires the $5 or 500 wii points, but apparently with the new lower price of Wii, Nintendo now throws in this Opera browser as a free downloable item! So if you just bought or Wii or didn't want to waste $5, now you can get it absolutely free!