Not signatures but if you are lucky may be able to take part in a few airdrops. Most dont drop to newbs but some are kind enough to do so
Airdrops are the same as signature campaigns or "signatures" as this guy calls them. The advertisement you're putting in your signature is for a new cryptocurrency that someone is scheduling for release in the near future. These releases are called initial coin offerings (ICOs). Instead of paying you in bitcoin they offer to give you some predetermined allotment of coins from the ICO. The coins are payment for your time spent making posts while they're advertisement is in your signature.
Actually, these aren't "airdrops"...they're payment for services rendered. An airdrop refers to when a coin splits (like how Bitcoin Cash was created) and the new version of the coin, to survive, needs to grant a number of the new coins equal to the number one owns of the original version of the coin.