Welcome to Challenge h2g2, the place where you, the h2g2 Community, can alert your peers to gaps in the Edited Guide. So if you've noticed we have entries on every element of a topic except one, here's the place to tell everyone about it.

So get your thinking caps on and find the missing entries. It could well be that someone sees your suggestion and is inspired to plug that gap. And if someone nominates an entry that you'd like to work on, let them know - it might well be that other Researchers will be only too willing to give you a hand.

For a limited period, every now and then the h2g2Editors will start a thread below asking for Researchers to write an Entry. Post first and you could end up the proud owner of an h2g2 T-shirt and badge. You'll know when the h2g2Editors start an Editors' T-shirt Challenge thread (currently available in sizes L and XL); it will be in the following format:

**Editors' T-shirt Challenge: The Career of Bruce Forsyth **

The first person to accept the challenge and carry it through to glorious fruition, meeting the exacting standards of all concerned (ie, when the entry has passed through Peer Review successfully), that person will be the recipient of an h2g2 T-shirt and button badge.

It's only the person who posts first who will be considered a T-shirt challenger. You accept the challenge with the words "I accept the challenge".

Entries will be expected to meet the normal Peer Review standards, and T-shirts will be sent out on the day that the Entry in question hits the front page. And remember this is an experiment; so the Editors' T-shirt Challenge will be occasional, random, and for a limited period only.

• We've got lots about the Beatles, but we could really do with entries on other big bands from the 1960s whose influence can still be felt today - notably The Who.

• We'd love a complete set of British monarchs.

• The life of Jesus Christ - and how it's described differently in each Gospel.

• Filmmakers such as Steven Spielberg, George Lucas and Woody Allen.

• New Hampshire and Oklahoma are the only US States that don't have any entries to their name. Can you help?