I was overseas about two years ago and had brought my electric guitar but no amp (thinking I that I would be able to find some sort of practice amp there). I ended up not having an amp for around three months.

For the first two weeks I got my fix by practicing scales and whatnot. But I finally got sick of not being able to hear myself, and I put the guitar in its case.

After a week of not playing I was itching for some riffage, and I finally borrowed a junk nylon string acoustic from a neighbor. It wasn't much, but at least I could hear what I was playing. (and I got pretty proficient at fingerstyle in the process)