[dorkbotpdx-blabber] Packaging markings -> part number lookup?

[Laen]

I've been scavenging a lot of boards with very tiny surface mount
components on them, and I don't know what a lot of them are.  Their
packaging markings don't turn up any obvious hits on google.

Does anyone know a good place to look up these chip markings and find
out what their manufacturing part number is?  Is there a database of
such things?

For example, right now I have three UA TO-92 form-factor chips that I
suspect are hall effect sensors.  The very tiny chip marking says
"Z06S 05L".  There are no other manufacturer markings that I can see.