About UNLIMITED service:

"UNLIMITED" USAGE POLICIES AND DEFINITIONS (from terms and conditions page http://www.bluehost.com/cgi/info/terms.html)

1. What "Unlimited" means. Bluehost.com does not set an arbitrary limit or cap on the amount of resources a single Subscriber can use. In good faith and subject to these Terms, Bluehost.com makes every commercially reasonable effort to provide its Subscribers with all the storage and bandwidth resources needed to power their web sites successfully, as long as the Subscriber's use of the service complies with these Terms. By not setting limits on key resources, we are able to provide simple, consistent pricing to our Subscribers as they grow their websites. As a result, a typical website may experience periods of great popularity and resulting increased storage without experiencing any associated increase in hosting charges.

2. What "Unlimited" DOES NOT mean. Bluehost.com employs complex mechanisms to protect its Subscribers and systems from abuse. Bluehost.com's offering of "unlimited" services is not intended to allow the actions of a single or few Subscribers to unfairly or adversely impact the experience of other Subscribers.
   Bluehost.com's service is a shared hosting service, which means that multiple Subscriber web sites are hosted from the same server and share server resources. Bluehost.com's service is designed to meet the typical needs of small business and home business website Subscribers in the United States. It is NOT intended to support the sustained demand of large enterprises, internationally based businesses, or non-typical applications better suited to a dedicated server.
   Bluehost.com will make every commercially reasonable effort to provide additional resources to Subscribers who are using their website(s) consistent with these Terms, including moving Subscribers to newer and bigger shared servers as necessary. However, in order to ensure a consistent and quality experience for all Subscribers, Bluehost.com does place automated safeguards to protect against any one site growing too quickly and adversely impacting the system until Bluehost.com can evaluate said sites resource needs.

3. Unlimited Hosting Space; excessive MySQL files.Bluehost.com does not set arbitrary limits on the amount of disk space a Subscriber can use for the Subscriber's website, nor does Bluehost.com charge additional fees based on an increased amount of storage used, provided the Subscriber's use of storage complies with these Terms. Please note, however, that the Bluehost.com service is designed to host websites. Bluehost.com does NOT provide unlimited space for online storage, backups, or archiving of electronic files, documents, log files, etc., and any such prohibited use of the Services will result in the termination of Subscriber's account, with or without notice. Accounts with a large number of files (inode count in excess of 200,000) can have an adverse affect on server performance. Similarly, accounts with an excessive number of MySQL/PostgreSQL tables (i.e., in excess of 1000 database tables) or of database size (i.e., in excess of 3GB total MySQL/PostgreSQL usage or 2GB MySQL/PostgreSQL usage in a single database) negatively affect the performance of the server. Bluehost.com may request that the number of files/inodes, database tables, or total database usage be reduced to ensure proper performance or may terminate the Subscriber's account, with or without notice.

4. Unlimited File Transfer. Bluehost.com does not set arbitrary limits on the amount of visitor traffic a web site can receive or on the amount of content a Subscriber can upload to his/her/its website in a given month, nor does Bluehost.com charge additional fees based on increased use of bandwidth, as long as the Subscriber's use of the Services complies with these Terms. In most cases, a Subscriber's web site will be able to support as much traffic as the Subscriber can legitimately acquire. However, Bluehost.com reserves the right to limit processor time, bandwidth, processes, or memory in cases where it is necessary to prevent negatively impacting other Subscribers.

5. Unlimited Domain Hosting. Bluehost.com does not set arbitrary limits on the number of domain names a Subscriber can associate with the Subscriber's web hosting account.