1. Windows azure
Windows azure trial offer, giving 200$ free credit to test out their services. Its a 200$ free credit trial or 30 days. (free 20 core)

Windows Azure Free Trial: Try Windows Azure | Azure Free Trial

2. Aws Amazon
A free 100$ credit on Amazon AWS that can be used on the EC2 service. (CPU and GPU, good for mining coin.) Working 12/11/2013

Power of 60: Get Started with Amazon Web Services

3. HP Public Cloud
Free trial period begins on date you create your new HP Public Cloud account. Promotional offer will appear as a $50 credit to each of your first three HP Public Cloud monthly invoices. If your usage exceeds this $50 credit in a billing cycle, you will be charged standard HP Cloud pricing for any additional usage.

Sign up today. Try HP Public Cloud free for 90 days | HP Public Cloud

4. Dimensiondata (Kill off the account if mining here)
Limited time trial offer for 200$ from Dimensions Data, they charge a hourly rate on servers.

https://nacloud.dimensiondata.com/limitedoffer/

5. Eucalyptus
Build a Private Eucalyptus Cloud | Get Started | Eucalyptus

6. GoGrid
You can request 30 days trial or use the coupon code to get $50 FREE CREDIT.
Coupon Code: CLOUDTRIAL (expire soon)

https://securesignup.gogrid.com/

7. Joyent Cloud
$65.00 of usage value per calendar month for up to 2 months. Total $65+$65=$130.

Free Trial - Joyent

8. InstaCompute
With a 30-day trial of InstaCompute.
They will call you within 24 hours or less to set up your free trial. Please note that you must provide a valid business phone number and email address in order to activate your account. You will be able to deploy cloud resources as soon as your account is verified.

http://instacompute.com/pricing/free-trial/

9. Terremark
http://www.theenterprisecloud.com/trial/vmware/

10. DigitalOcean (Good and cheap for mining coin)
Use promocode : DIVEIN10 for $10 credit
Updated January 3, 2013 (working)
Add $10 to balance with code: OMGSSD10
https://www.digitalocean.com/

Add in:

11. Liquidweb
Get $75 free coupon for storm cloud servers (liquid web)
https://www.stormondemand.com/campai...wc4ixdATGGmBk8

PS: Most of them need a valid Credit Card to create free trial account.
 buy a cheap vcc to try.