A uuid seems excessively long. I sorta like the idea of base64 encoding it (or just using the first 32 bits) but that is  mainly an aesthetic thing. Something like:
```sh
python -c "import uuid; print uuid.uuid4().bytes.encode('base64').rstrip('=\n').replace('/', '_').replace('+','_')"
```
that generates shorter unique id's like:
`mrjuSg0qRhCOcgaqstMOKw`