Can you transfer a domain for free, without renewing it? The registrars I've seen so far all require you to buy an extra year's registration, but I'm not sure if this is a requirement of transferring a domain or not.
This normally depends on how close you are to the domain's renewal date, but to pay for a domain transfer is normal practice. If the domain is approaching expiry then often renewal will be required at the time of ordering the transfer. To clarify:
Some examples (from Enom's Domain Name Pricing page):