tag generation from a text content
A very simple solution to the problem would be:

count the occurences of each word in the text
consider the most frequent terms as the key phrases
have a black-list of 'stop words' to remove common words like the, and, it, is etc

I'm sure there are cleverer, stats based solutions though.
If you need a solution to use in a larger project rather than for interests sake, Yahoo BOSS has a key term extraction method.
I am curious if there is an algorithm/method exists to generate keywords/tags from a given text, by using some weight calculations, occurrence ratio or other tools.
Additionally, I will be grateful if you point any Python based solution / library for this.
Thanks