Avatar Press publishes a free online comic every Thursday with Crossed: Wish You Were Here.
Crossed is an over-the-top, adults-only outbreak story created by Garth Ennis (Preacher, The Boys, Chronicles of Wormwood) in 2008.
Wish You Were Here is written by Si Spurrier (X-Men Legacy, Judge Dredd, 2000AD), and features a ragged band of survivors holed up on a small island fighting off the horror of the Crossed.
The first 22 chapters were recently collected in soft and hard cover editions. However, you can read the individual web chapters for free here.