The Daily Caller has an interesting story, naming some names, about ostensibly independent political bloggers who take cash from political parties and partisan organizations. The site names names of conservative bloggers who take the money (some of whom are sophisticated enough to take the cash as "advertising" or "consulting fees") and alleges the same thing happens on the left, although the article doesn't cite examples. The Daily Caller leans right, so perhaps it has better sources on the right side of the political divide.
I've never been offered any money, either for this blog or for any that I do on my own. Perhaps people sense that I am incorruptible, or perhaps they realize the money would be better spent on a blog with a mass audience.