Here are some words which contain a silent <s>.
aisle apropos bourgeois chassis corps debris hors-d’oeuvre island isle(t) lisle patois precis viscount
And here are some place-names which contain a silent <s>.
Arkansas Des Moines Grosvenor Illinois
I’ll add to both lists when I (or somebody else) think(s) of other examples.
Thanks to Petr Rösel for additions
2013_09_20
Updated 2013_09_25