The Trésor de la Langue Française, a digitized corpus of French literature, now allows direct links to words. For example:
gets you citations for ‘dégringoler’ (note that accents should be omitted).
Jean Véronis at Technologies du language has made a search form.
Here’s the code:
<form action="http://atilf.atilf.fr/dendien/scripts/fast.exe" method="get">
<input name="mot"><input value="TLFi" type="submit"></form>
He has also made a plugin for Firefox.