You can use an underscore to represent a space, so "John_Smith" will only match those two words in a row.
You can join words with an asterisk to say that they may only be 20 characters apart. For example, "John*Smith" will match John Smith, Jonathan Smith, and Johnathan Midlename Smith (or for that matter John "Big Boy" Smith).
You can preceed a word with an exclamation mark to negate it (that is, to exclude articles that use the word). For example, "!Smith" would leave out any article that mentions a Smith. In practice this is really not very useful. But if you add an asterisk it can sometimes be handy. For example, if you search for "John*Smith !Jane*Smith" you should get every article about John that does not also mention his sister Jane.
NB: Our archives are missing several issues and only go back to March of 2008.