IRIS: Digital repository of instruments and materials for research into second languages. Search, download and adapt materials for your own research.
PsycNet: You can search for materials that have an assessment instrument included in them.
Use one search box for your broad topic and then..
in another search box - type Appended and change the In: box to Test & Measures
ERIC: You can search for materials that contain an assessment instrument.
Change the Publication Type: to Tests/Questionnaires