Try 'which foo' maybe, or 'updatedb' and 'locate foo' - or, if it's large and you know about what 'du' should produce, do 'du' and look for what's expanded.
Or, just fire up a file manager and do a lot of wandering around in directories. If it's a binary some of it should have ended up in bin, of course - which bin might be a question, depending on the type of app.
And it's possible it just disappeared. *g* Stuff should untar - and unzip, I guess - in a new subdirectory in the same directory as the compressed file. Or, rather, it should unzip to the directory you're running the command from which, based on your quote, was the same as the zip.
Um, and of course, if this was on a mounted floppy none of the above except maybe du will work because it'll be on the floppy. And if it was from a mounted cdrom it should have given an error but might have exited silently - it would have unzipped to RAM but not written anything.