I love craft activities! There is a good website such as activityvillage.com which had lots of crafts depending on the different theme. After looking at these crafts my mind wanders and I go in search of things in my home that I can use and I make up my own activities. With craft activities I find it is useful when the children can see the example.
On another note and personal experience....
I took a group of children outside to do a 'number hunt' which linked in with mathematics, being outdoors and increasing their physical and cognitive development, so that they could find a specific hidden number. If they did not find the number I had asked them to find, I would give them clues and get them into pairs etc. When the children had found the number, they had to tell me what it was and match it up with some numbers I had on the floor.
When I was asked if I could do a maths activity, I was a bit 'oooohhh errrr how do I do that.' But after thinking and talking to the teacher, I planned and carried out the number hunt and the children and I had a good time.
Best of luck with what you do, little-roo