Following is the list of the various twitter accounts used by Google:
Company-wide
- Google Jobs
- Google Public Policy
- Google Research
- Google SMB (Small and Medium Businesses)
- Google Students
- Google Talks
- Google Ventures
Products and Services
- Blogger
- Blogger in Draft
- Data Liberation
- FeedBurner
- Gmail
- Google At Work
- Google Books
- Google Calendar
- Google Chat
- Google Contacts
- Google Custom Search
- Google Finance
- Google Images
- Google Knol
- Google Mobile
- Google Mobile App
- Google News
- Google News Japan
- Google Reader
- Google Realtime Search
- Google Sidewiki
- Google Sites
- Google Students
- Google SXSW
- Google Toolbar
- Google TV
- Google Voice
- Google Wave
- Google Webmaster Central
- iGoogle
- Internet Bus
- Panoramio
- Picnik
- YouTube
Geo
- 3D Warehouse
- Google Building Maker
- Google Earth
- Google Earth Outreach
- Google Mapmaker
- Google Maps
- Google SketchUp
- Google Sky Map
Developers
- AdWords API
- Android Dev
- App Engine
- Closure Tools
- Google APIs
- Google Apps Developers
- Google Apps
- Google Code
- Google Code Jam
- Google Code Jam Japan
- Google Developers Brazil
- Google Developers Japan
- Google I/O
- Google Maps API
- Google Quick Search Box
- Google Developer Day Russia
- Google Summer of Code
Countries and Regions
- Google Africa
- Google Arabia
- Google Argentina
- GoogleAtWork Japan
- Google Brazil
- Google Canada
- Google Down Under (Australia and New Zealand)
- Google Germany
- Google Hungary
- Google India
- Google Italy- Policy
- Google Japan
- Google Korea
- Google Kyrgyzstan
- Google Latin America
- Google Maps Japan
- Google Mexico
- Google Netherlands
- Google Netherlands Business
- Google Russia
- YouTube Spanish
- YouTube Netherlands
- YouTube Portuguese
- YouTube Japan
Advertisers and Marketers
- AdWords French
- AdWords Helper
- AdWords Pro Sarah
- DoubleClick
- Google Analytics
- Google Analytics Brazil
- Google Creative Sandbox
- Google TV Ads
- Google Auto (Vertical)
- Google Display
- Google Financial Services (Vertical)
- Google Grants
- Google Media and Entertainment (Vertical)
- Google Mobile Ads
- Google Retail (Vertical)
- Google Tech (Vertical)
- Google Travel (Vertical)
- Google Travel UK (Vertical)
- Google Technology UK (Vertical)
- Google UK Retail (Vertical)
- Google AdWords- German
- Google AdWords- Latin America
- Google AdWords- Russia
- Google AdWords- Spanish
- Google Agency- Germany
- Google AdWords- Brazil
- Google Ad News- Latin America
Online Publishers
[Source]