We have a chalkboard wall in our house and it is the best thing ever. It means he can practice his writing or drawing whenever he likes and without the fuss of setting up the table and dragging out paper and pens. The other day he was drawing on the wall and I happened to mention to him that one of his drawings looked very much like a y. I could almost see the lights going off in his head and he started practicing his y's straight away.
Today I took it a step further and with some gentle encouragement (in the form of a small toy) he wrote his name pretty near perfectly. He was absolutely bursting with pride (as was I).
There'll be no stopping him now. He loves showing off and once he can do something (and he gets such a good reaction from it too) he keeps on doing it until the next 'new' thing, but as the saying goes "practice makes perfect".