NRICH presentations at the UKMT Teachers Meetings 2007
Put the word poster into the text search box (top right on any NRICH page) to see a small collection of posters which have been available on the NRICH site during the last two years.
Squares in Rectangles (August 2006) is the one printed for your delegate pack.
This link takes you to the poster and this link takes you to the problem where you'll find teachers notes and student created solutions.
Semi-Regular Tessellations has a nice interactive environment - use the print screen button (Prt Sc ) to capture the design created and then paste into the application of choice (Word, PowerPoint, Paint, etc.)
There were three problems which were offered for moments when you wanted a distracting idea to play with.