The only one I know is
https://forum.bitcoin.com. But they rarely have good paying signature campaigns.
You could check Micro Earnings section (
https://bitcointalk.org/index.php?board=212.0) and this section, Services, few pages back. If i remember correctly, there are 2-3 forums offering paid to post in there. But the rewards are a lot less than here.
I have red about them, one of my friends also joins them and it is not worth our time, they have limited campaigns, maybe because they are just new or just started, I really don't know and don't mind them anyway, I just focus here I am happy with what we have now.
