Use UserVoice to manage suggestions
 

UserVoice is to suggestions, what Jira is to bugs.
Not only allows it to suggest features, but also to:
- vote on suggestion
- discuss the suggestions
- users are guided trough a series of suggestions and are asked to vote on them.
- its very easy to see what the most wanted features are.

UserVoice works very well for other Software Development companies, so vb should definitely benefit from this.