Tube Toolbox is software that you download and run on your computer.

It automates your daily marketing tasks, which allows you to reach up to 100x more YouTube users than you could on your own. Tube Toolbox can run in the background while you work on other projects or even while you sleep. The process of using Tube Toolbox is broken up into two steps:

Step 1: Gathering Users Target your Audience
The first step is to find people on YouTube who you believe would be interested in your YouTube Channel or Video. Tube Toolbox has many features to help you find and target these people.

Step 2: Contacting Users Automate your Tasks
The second step is to use our automation tools to contact the people you gathered. You do this by having Tube Toolbox send Friend Requests, Messages and post Comments. This will bring people to your Channel and Videos ultimately increasing your video views and exposure on YouTube.

Features:
Account Safety
100% Money Back Guarantee
100% YouTube Terms of Service Compliant
YouTube Data API Integration
Automated wait/retry when YouTube's Sending Limits are Reached
Send Delay Options to Protect your YouTube Account
Automated Tasks
Friend Request Sending
Message Sending
Send Messages from Multiple YouTube Accounts to Ensure Maximum Sent
Multi-Message Sending Rotation
Include Unique Channel name in each Sent Message
Multiple CAPTCHA Options & Bypasses
Comment Posting on User Accounts
Comments on Videos
Share Video (with Message) to Multiple Users at Once
Automated Subscription Invite Sending
Automated Unsubscribe from Channels
Accepting Friend Requests
Gathering Features
Gather only Selected Users & Videos from page
Auto-Gather User's Friends
Auto-Gather User's Videos

Check out this blog post to see how one user is getting 1000 friends per week with Tube Toolbox:
http://www.quickregister.net/wordpress/2011/01/15/how-i-am-getting-1000-youtube-friends-per-week-on-auto-pilot/