You can browse to <i>any</i> web app. 
"Limit" is very relative - there are more on-the-metal apps available for the iPhone than any other phone, no?<p>And not only that, but you get probably the best mobile phone browsing experience; although I have not tried the Nexus One yet (because there's no customer support), but I am willing to eat an onion if the Nexus is better. I know the BlackBerry sucks at browsing.