Opera have released Opera Mini, a free web browser for mobile phones. Opera will SMS you the 64 kbytes of Java code (for a fee), you can install it via a PC, or as I did, got it on your mobile phone's existing browser.
But if you phone already has a browser, why install Mini? It reduces the size of images, compresses data and reformats web pages to fit better the phone. Mobile phone bandwidth is limited and phone companies charge a lot for data (mine charges about $20 a megabyte). It is a waste to download a large image on a web page only to have it shrunk to fit on the tiny phone screen (mine is a large one, but still only 320 x 240 pixels). Opera acts as a smart cache shrinking the image before it is sent to your phone.
Pages are also rearranged to fit better: Mini arranges the columns of a web page one after another. the width of the phone screen. This works well for web pages designed for accessibility and ones designed with a phone option (as mine are). But it doesn't work as well with poorly designed pages.
Opera also chop the web page into small portions, sending only a portion to the phone. This saves on download time and cost.
The result works quite well. My home page comes up with the logo at the top, the main menu, text, and most impressively of all, the Google advertisements at the bottom. My Blogger web pages also work well.
Apart from the browser built into the phone, alternatives are Google's XHTML converter. Like Opera Mini, this converts web pages to a mobile friendly format (XHTML Basic) but it removes images completely and has much more limited formatting.
One catch with Opera Mini could be that it is so easy to use you could run up a big bill without care. While it reduces the cost of data traffic, there is still data going back and forward and the pages pop up so quickly it is tempting to go surfing around.