Here is a list of useful websites offering all kind of services for free:

1. https://mega.nz

One of the best sites to share files with 50 GB of free space.
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2. www.midomi.com

The best site to find songs by singing or humming them.
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3. www.mp3juices.cc

A great site where you can download mp3 music for free.
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4. www.downforeveryoneorjustme.com

A site where you can check if a site is down for everyone or just for you because it is blocked, your IP is blocked or you have a connection problem.
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5. www.systemrequirementslab.com

A site where you can check if your computer can run a certain game selected from a list of games.
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6. mp3cut.net

A site where you can cut songs online in just three steps and create your ringtones.
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7. cleverbot.com

A site where you can chat with a program of artificial intelligence.