That's not leaving the PC on, that's wasting my time for little reward.
If you mean electricity, you're not making money. You're saving money. Couldn't hold myself. :p
Basically instead of having your personalised signature you rent that space out to advertisers on this forum.
Search "signature campaigns" and you'll find a list of it.
But signature campaigns doesn't count as "making money by leaving your PC on" IMO.
Doesn't sound that bad, assuming I would keep having something to say and post about. Side income though, doesn't count as what I needed. But yea, good idea, I didn't know that existed. It explains why on some other forums I see sigs that look like ads and make me wanna block them.
Thanks for the suggestion.