How to do a simple find-replace autocomplete?

[Mats Ahlgren <mats_a@xxxxxxx>]

Hello,

I'd like to do a simple autocomplete, where a string (e.g. #doc) gets expanded instantly into '/home/username/documents' or somesuch

I've been searching online for a long time on how to do this, but couldn't find any information.
Would someone be so kind as to suggest a reference or provide the code snippet?

Thank you,
Mats