I am wondering where to know who is offering signature campaign? Is there a section which is listing all campaigns?
You can go to the services section that can be found here
https://bitcointalk.org/index.php?board=52.0And make sure that you'll read the campaign's rules so that you have an idea if you are qualified to join the campaign.
If you want to earn some alt coins from ICO's and other bounties that you can exchange for bitcoin.
You can redirect to the marketplace for alt coins here
https://bitcointalk.org/index.php?board=161.0