govtrack.us and it's sister site popvox.com. On govtrack I have trackers set up for my senators and the representative from my district, some general trackers, and some trackers for specific bills. I get a daily update (but weekly is an option) of activity related to my trackers. Popvox lets you approve/disapprove of bills.

Govtrack SOPA page: http://www.govtrack.us/congress/bill.xpd?bill=h112-3261

Popvox SOPA page https://www.popvox.com/bills/us/112/hr3261