Fizzygoo covered most of the ones I would suggest. In addition, I would run the occasional "acquisition" of human resources from other corps, and when they need a challenge, the red alert run where they have to stop an infiltrating team from completing their own shadowrun (for a real twist, have one session where the players play characters that are making the shadowrun, then the next session they can play the spec-ops team trying to defend against them. Just use a third tier daughter corp name, and stop the first session when the spec-ops team shows up). Other than that, unless you want an open corp war going on, that's all I have.