One of the absolute biggest gripes that I have with websites seems to have turned into a hot "feature".
I absolutely despise it when websites insist on setting focus to a control on a website after its finished loading. The issue really comes into play on the "improved" http://www.msn.com. On this site now, the focus automatically comes to the search textbox towards the top of this page. This is quite frustrating, since this is my browser's homepage. Because of this feature, 75% of the URL that I type into the address bar ends up in this search textbox. ARGH.
Other lovely uses for this feature are on some of my credit card sites, where I type my username, hit tab and get halfway through my password, when it sets the focus to the username field, promptly displaying the second half of my password in the username field.
Have any website gripes of your own? Feel free to comment.