Favorite Speed Workouts -- Advice??

So I have been slowly getting back into competitive running after taking a very long break that coincided with my daughter being born and a crazy year-long renovation of a Fed Hill rowhouse. Anyway, my mileage is starting to increase -- about 30-40 right now and I'd like that to be 45-55 in the next month or so -- but I'm struggling a bit to assemble some speed workouts. It's been a while since I have "trained" for anything, but I'm feeling great in my runs lately and I really hope to drop some PR's in the next 6-12 months or so.
So here's my upcoming race calendar. There's a big run in Hawaii called the Great Aloha Run. It is 8.15 miles and is February 15th. This is my "goal" race, if you want to call it that. There is also a Readiness Series leading up to the Aloha run consisting of a 5k (12/7), an 8k (1/10) and a 10k (1/31) that I'd like to use as part of my training.
So here's my question for the group -- what are some of the best speed workouts you have done in the past year? What have you found the most effecive? What has worked at TNT? What hasn't worked out so well?
I have a smal group of strong runners here that I run with twice a week - Wednesday night group runs of 6-9 miles and Sunday long runs of 12-18 miles so far. But my speed work may be done by myself, unless I can convince any of them to join. There are also plenty of hills around here if you have any good hill workouts to recommend. Sidenote - I went for an "easy" hour run yesterday and stumbled on a ridiculous hill half way through the loop I wanted to do. I wish I knew the elevation on it, but it was a good 1/2 mile of climbing. Ugh.
Anyway, I appreciate any help you can offer. I also hope this helps others in the group by compiling a list of quality workouts we may want to use over again in our training cycles.
Thanks!!