Here’s a few points to note as a follow up to the Need More Power? post.

Word Exceptions

• Commonly used words like ‘a’ and ‘the’ are usually ignored, but there are exceptions [the hobbit]
• To avoid synonym replacement of words in a query, insert a ‘+’ before the word to disable this feature
• Google may omit a word from the query if other evidence indicates that the page is relevant

Watching Punctuation

• Terms containing punctuation with a specific meaning are not ignored: [ASP.NET]
• The dollar sign will change results, delivering price-related information: [iPod 60] vs. [iPod $60]
• The hyphen can be used to indicated a strong link between two words. Note that a space before the hyphen will change this indication to a negative sign and omit the attached term from the search. [video game] vs. [video-game]
• The underscore symbol can be used to connect two words [video_game]

[Background information provided by Google Web Search Help]