Every single day, I receive at least one email asking if I’ll accept cash for adding a link to someone’s website in an old post.
I won’t. Not ever. Please stop asking.
I can imagine a world where, if my website and newsletter became more of a full-time endeavor, I’d accept patronage. Daring Fireball and Pixel Envy are two personal blogs that have weekly sponsors; I don’t mind this at all as a reader. Maybe I’d consider that.
But if your goal is to juice Google’s algorithm by spammily adding links in authoritative old posts, the answer is always no. If you have to promote your site using these techniques, their quality is probably very low, and my site will suffer as a result of linking to them; the amount of money is also not worth me considering.
I’m not opposed to making money from my site. But if I do that, I want to do it in a way that’s above board, aligned with my community, and that is worthwhile for everyone involved. In the meantime, I’m just going to keep writing for me.