Usability 
Vanguard Funds is a large US mutual fund house specializing in no-load, low cost index funds. I'm a Vanguard customer and I like the company but I'm disappointed by their mobile site at vanguard.mobi (you will need a mobile browser to see the mobile version). There isn't much content and usability is not as good as it could be.
Vanguard.mobi can be used by anyone, whether they have a Vanguard account or not, to view the current value of four major US market indexes and read financial and market news sourced from Reuters. That's assuming you can actually read the text. Vanguard.mobi's stylesheet sets the font size of various elements on the page to between 40 and 70 percent of normal. Many mobile browsers ignore font size, but for ones that honor it, like NetFront (lower image), Vanguard.mobi is very hard to read at default browser settings. It's good practice on both the full web and the mobile web to use the default or 100% font size for main text, virtually guaranteeing that it will display it in a readable size.
For Vanguard customers there is an enticing "My Portfolio" link. To get to your account you have to log in, of course. That's another area where usability breaks down. The mobile site's log in link takes you to a non-mobile formatted log in form that requires you to answer an additional security question and verify your personal security image. The log in process was cumbersome, but at least possible in testing with the Openwave browser found on many low end phones.
It didn't work at all with the Motorola MIB browser found on many of that company's feature phones. Log in isn't persistent so you have to repeat the process every time.
Upon finally reaching my portfolio, I was disappointed that all I could do was view the last 72 hours worth of transactions and the combined dollar balance of the entire portfolio. There is no way to drill down and view the performance of the individual funds making up the portfolio.
I really wish Vanguard.mobi were a little more useful. I'd like to see some of the features of Vanguard's full web site extended to mobile like the ability to research current prices and yields of individual funds, set up watch lists and view more detailed information about my own portfolio's performance.