If you travel and collect guidebooks...great. What happens when they get old, outdated or you are just not going to use them again? Dust collectors? Book shelf fillers? Food for your storage closet?
Recently I came across some suggestions and have added some of my own. Take a look...
You could always sell them online. www.guidegecko.com allows you to list guidebooks for free and then takes a 15% commission when they sell. There are other sites as well. And just maybe someone is looking for a guidebook on Los Angeles or cheap sleeps in Italy.
Some bookstores buy gently used books. Check out your local store to see if they have such a program.
You could trade them. Look at Swaptree to see how they work.
Give them to a friend...provided the friend wants them.
Leave them. You are finished in Finland and know you won't be coming back in the near future...leave it with the B&B owner. Just don't leave it in your room. You may get it mailed back to you!
Give them to a library. Any gently used books are welcome and you can ask for a receipt for tax purposes.