Skype has introduced a set of Marvel super-heroes emoticons to the chat messaging side of the service to coincide with the release of Captain America: The Winter Soldier on 28 March in the UK, 4 April in the US.

Currently, there are four in the range, representing Captain America himself, Bucky, Nick Fury and Black Widow. There's a secret fifth emoticon of Cap's shield too, which can only be unlocked by completing a "challenge" on a dedicated website. There are three questions you must answer with the help of Bing Maps, the official trailer and a bit of character knowledge.

Not everyone can see the emoticons yet as you will need to install the very latest Skype update and that's currently rolling out across territories. We've managed to get it working on one PC, for example, but not another. And can't get them working yet on Macbooks.

Patience though as it's only a matter of time.

Skype also offers other Marvel Studios goodies to download from its Hero Hub, such as wallpaper and avatars. Plus, you can nominate a real-life unsung hero and if selected they will receive a recorded salute by one of the stars of the film.

To use the emoticons in Skype, type (captain), (bucky), (nickfury), and (blackwidow). We'll leave the last one for you to discover.