Fun read!
The Decker seems to have the coolest combos. It's been many months, but I will try to remember correctly.
In my hand : Hack the World, Mark, Pair programming and other colors. In my discard, Jacked In and Retrieval Agent (among others). In the Black market, there were another Retrieval Agent.
My Play : I use Hack the World, get the Retrieval Agent from the Black Market, use it to get the another Agent from my discard. Also, I discard my Mark and replace it with the Jacked In. I attack with all my cards, except with my last Retrieval Agent (I keep it in my hand). When it's again my turn, I use my retrieval Agent to get my Hack the World back from the discard and another round of high damage begins. It was fun, but it was a rare occurence.
A more common combo that I like to use (for the Mage) : Deathtouch and Stunbolt. Use Deathtouch, look and rearrange the first 3 cards of your deck in a way to make sure that Stunbolt does a lot of damage. Using Deathtouch before Clairvoyance can be useful too.