I often just use the word Bush for search at Yahoo it means you have to wade through loads of rubbish and of course recently loads of Reggie Bush but it does turn up photos that otherwise under President or George or Laura Bush do not appear.
Gretchen gave me a helpful tip. Instead of searching for "President Bush" she suggested I try "+ 'President Bush'- moore". It eliminates almost all of the garbage out there (and there's a lot of it :-/)