I normally fold from ~10 * 10cm (Thanks to spiritofcat for realizing my error in originally putting 10cm²!)
There are some excellent suggestions above (Particularly Forcher's Fox '96)
Here are some of the most complex & pleasing models I reliably produce to a satisfactory finished model, in terms of appearance and neatness, from very cheap (Copy Paper) of that size. They are intermediate to complex, none would be considered super-complex by todays standards.
Also listed is where the instructions are to be found - they are all full diagrams, and should be pretty easily obtainable sources.
Robert J. Lang - Ant (Origami Insects & Their Kin)
Robert J. Lang - Hercules Beetle (Origami Insects & Their Kin)
Robert J. Lang - Mouse (Origami Zoo)
Robert J. Lang - Rabbit (Origami Zoo) - Though difficult at this size.
Robert J. Lang - Murex (Origami Sea Life)
Stephen Weiss - Dog in a Doghouse (Origami Zoo)
Stephen Weiss - Duck (Origami Zoo)
John Montroll - Weevil (Origami Sculptures)
John Montroll - Asparagus Beetle (Origami Sculptures)
John Montroll - Fox (Animal Origami for the Enthusiast)
John Montroll - Goldfish (Origami Sea Life)
John Montroll - Cichlid (Origami Sea Life)
John Montroll - Baracuda (Origami Sea Life)
John Montroll - Lion (African Animals in Origami)
John Montroll - Wyvern (Mythological Creatures & the Chinese Zodiac in Origami)
John Montroll - Western Dragon (Mythological Creatures & the Chinese Zodiac in Origami)
John Montroll - Earwig (Bugs & Birds in Origami)
John Montroll - Butterfly (Bugs & Birds in Origami)
Fumiaki Kawahata - Jedi Master Yoda (AEP website)
Noburu Miyajima - Horse (Miyajima-San's Website)
Toshikazu Kawasaki - Supersonic Reconnaissance Plane - SR-71 'Blackbird' (Origami for the Connoiseur)
Quentin Trollip - Danger! (Mr. Trollips Flickr Account - "Quentin Origami")
Mark Kirschenbaum - 'Fluffy' (origami.com)
Jerry Barker - Acrocanthosaurus (origami.com)
J. Anibal Voyer Iniesta - Ghost (origami.com)
David Brill - Fairy (brilliantorigami.com)
Luis Fernandez Perez - Perro Liberando (Origami Kit for Dummies)
Go Guspath - Mouse (Origami Kit for Dummies)
8 Pointed Star - Peter Engel (Origami from Angelfish to Zen)
Kunihiko Kasahara - Llama (Origami Omnibus)
Edwin Corrie - Square Bear (Encyclopædia of Origami)
Hsi-Hua Liu - Fish (Mr. Liu's Flickr Account - "hsi-hua"
Other more complex models can be folded from cheap paper at this size (even by me on occaison) but they are overly difficult & the finished product is unsatisfactorily thick and messy.
Gilad Aharoni's excellent website has pictures of all of these models, and reviews of the books where applicable:
http://www.giladorigami.com
NB: I don't have the most popular, expensive books like Kamiya's or Tanteidans. So, unfortunately, I can't comment on how those excellent models fold. I'm sure many others can help in that regard.
Good luck! Hopefully you can post pictures of whatever you decide to fold.