The most famous and nourishing passage about grace in all the Bible is I think Ephesians 2:8-9 and if I could recommend one sermon that might unlock grace for you this one might be it. I've been going through Ephesians on and off all year with M L J (one word at a time so we're only in Chapter two!). The sermon 'By grace through faith' will simply blow your doors off (on iTunes Dec 12 podcast or from the MLJ archive). You'll especially love it if you like your preaching Welsh and a tad humourless. 'Bear with' and again I say 'bear with'. Sit in the chair, listen and much like the words on a shampoo bottle 'rinse and repeat as necessary' until Jesus explodes in your heart.
I also listened this week in the car to Humble Confidence preached by Jonathan Martin (one of my favourite preachers) which is wonderful and really really blessed me. It's number 23.