For anyone looking to do Strength in Numbers:
Myself and a friend (both of us have 2 pads for 'Guests') are currently boosting L4D2. We're usually on around 7pm-11pm GMT weekdays (bar Friday and Saturday) and earlier on Sundays.
We need min 2 more people each with a spare pad but the more the merrier.
My GT is CompanyOfWolves so send me a mail and invite on Xbox Live if you'd like to join us. Please don't send a friend invite without a mail.