Something to keep in mind for future conferences is perhaps a wiki page (world-writable) for lost-and-found. I ended up with a Medion brand USB stick, 64MB, with .tex source files on it and a bunch of PDFs and some family pictures. The TeX sources look have this attribution:

\author{Departamento de Matematicas \\ I.E.S. Santa Maria de Guia}
\title{PO. Numeros enteros}

It's primary school quizzes on whole numbers! Was found in the music hall, but I haven't had time to notify about it yet. I will take it to the conference at the ULPGC and leave it at the desk there. (Wasn't there a news item recently about the dangers of plugging in random USB sticks? And if you're looking for objects, consider this method.)