seo friendly(google like) much mod rewrite replace space with dash or dot or underscore? [ex. worldwideweb.xxx.com/i-love-you or worldwideweb.xxx.com/i.love.you or worldwideweb.xxx.com/i_love_you]
I think the first and the last one will be better than the middle one. Google can handle "-" and "_", but I'm not sure whether it can handle "." under this case.
Use the dash or the underscore in your URL's for the engines to read the links properly. Trying to separate each word with a period and setting the rewrite rules is more work then it is worth and has no SEO benefit over using dashes or underscores.