Of course you repeat yourself. We all do. Some repetition is good to drive home your point in a story or essay, but too much is just too much.
So... I was checking through my Twitter Follows and found a useful site with word and phrase frequency counters. The Phrase Frequency Counter allows you to choose the number of words in a phrase to check (from 2-10). The Word Frequency Counter checks every word in your text. Both frequency counters allow you to cut and paste or type the writing sample you want analyzed.
These are cool:
Phrase Frequency Counter
Word Frequency Counter
For example, when I cut and paste the text above (including the blog title) into the Phrase Frequency Counter, I found out that I used the phrase "frequency counter" four times, "phrase frequency" and "frequency counters" three times each. Plugging in the same sample into the Word Frequency Counter, I found that I used the word "frequency" seven times, and "you" and "to" five times each.
Good to know - especially when writing for the Web.