cold frames, compost bins, those pyramid shaped thingies for climbing plants, potting bench.
Here's a link for the cold frames
http://www.allotment.org.uk/greenhouse- ... dframe.php
and i'm sure if you goooogle the interweb for how to make...... you'll find more plans.
oh, oh and a Dovecote! always wanted one and they sell for squidoons!!
Never been able to find any free plans for dovecotes though

and I have searched for hours.)