The effect on 10East.com is pretty doable (check out the source code for the page - you'll need to type in the address for the script, since it's not part of the main page).
If your server supports PHP, you may well not need to bother with JS. Its main advantage is that everything is done client-side, so people whose servers do not support PHP or CGI can reproduce some of the effects that these provide. The things I've used JS for (e.g. randomising text), I could have done more easily with Perl-CGI, but our university doesn't allow a non-CGI server to call CGI scripts (actually a pretty sensible security measure).
Re: Geek reply
If your server supports PHP, you may well not need to bother with JS. Its main advantage is that everything is done client-side, so people whose servers do not support PHP or CGI can reproduce some of the effects that these provide. The things I've used JS for (e.g. randomising text), I could have done more easily with Perl-CGI, but our university doesn't allow a non-CGI server to call CGI scripts (actually a pretty sensible security measure).