These are my favorite free psychological instruments.

Authentic Happiness Inventory Questionnaire

http://www.authentichappiness.sas.upenn.edu

DISC

http://www.gregwiens.com/scid/

http://www.tonyrobbins.com/ue/disc-profile.php

Emotional Intelligence (EQ)

http://greatergood.berkeley.edu/ei_quiz/

http://www.glennrowe.net/BaronCohen/EmpathyQuotient/EmpathyQuotient.aspx

http://kgajos.eecs.harvard.edu/mite/

Enneagram

http://helloquizzy.okcupid.com/tests/the-quick-amp-painless-enneagram-test

http://www.eclecticenergies.com/enneagram/test.php

Five Factor Model (Big 5, OCEAN)

http://www.personal.psu.edu/j5j/IPIP/ipipneo300.htm [300 items]

http://www.personal.psu.edu/j5j/IPIP/ipipneo120.htm [120 items]

http://apps.facebook.com/mypersonality/index.php [100 or 336 items]

http://test.personality-project.org/ [76 items]

http://www.personalitytest.org.uk [41 items]

Grit Survey

http://www.authentichappiness.sas.upenn.edu [22 items]

Johari’s Window

http://kevan.org/johari

Learning Styles

http://people.usd.edu/~bwjames/tut/learning-style

Myers Briggs Type Indicator (MBTI)

http://similarminds.com/myers-briggs-jung.html

http://www.okcupid.com/tests/16567335035599898597/LONG-Scientific-Personality

http://www.teamtechnology.co.uk/mmdi/questionnaire/

http://www.davenevins.com/personalities/main/findyourtype.htm

Philosophy Experiments

http://www.philosophyexperiments.com

Positivity Ratio

http://www.positivityratio.com/single.php

True Colors

http://helloquizzy.okcupid.com/tests/true-colors-test-a-self-inventory

VIA Survey of Character Strengths

http://www.authentichappiness.sas.upenn.edu

Writing/Reading Level

http://bluecentauri.com/tools/writer/sample.php