You actually get bonuses for posting in their forums

Posts - Allowance

100 - 50 MB disk space
150 - 500 MB transfer
200 - 5 subdomains
250 - 5 databases
300 - 1 Multi-Hosted domain
400 - 100 MB disk space
500 - Free Domain name
600 - 1 GB transfer
700 - 10 subdomains/5 databases
800 - 1 Multi-Hosted domain
900 - 100 MB space/1 GB transfer
1000- Free Domain Name

After you reach 1000, the cycle repeats itself.

Example: You are on NexBusiness-5 GB transfer, 100 MB space, 2 MultiHosted domains, 3 databases and 10 subdomains. Imagine as the forum gets busier, you post 5 times a day, 150 times a month. After 6 months you could have a plan that looks like this:

7.5 GB transfer
350 MB disk space
2 Free Domain names
4 Multi Hosted Domains
13 Databases
25 Subdomains

All for only $54.95 a year