If you've not read
Day by Day Armageddon by J.L. Bourne
Its a slightly weaker but still good story similar to WW:Z.
Lets hope the The Morningstar Strain strain books by Z.A Recht will be turned into eBooks soon. I have both in hardcopy and they're pretty good.
To be honest, I'm slowly working my way through the Abaddon Books catalogue, they're all pretty good reads, nothing that will blow your mind but all good books that wont dissapoint. But they need to get up to date with their ebook releases.