I forgot to mention that I work from home full-time as a Senior Software Engineer for a really great, family-friendly software company. This has both pros and cons. The pros are obvious - getting to spend all day with my kids and getting to work at the same time is a dream for most Moms. The con is that working from home means that I never get to leave work, so making a distinction between work time and family time is critical.
My work day starts early in the morning as I try to get as many things done before the family wakes up, and ends late in the day as I try to fit in any remaining work tasks after the kids have gone to bed. My manager doesn't mind what schedule I work as long as I put on the calendar so others can schedule meetings around my availability. I've found that blocking out specific hours during the day on my company calendar as 'unavailable' has helped me dedicate those blocks of time solely to homeschooling activities without drifting back to my computer to check email and get work done. The girls are great at entertaining themselves (and each other) the rest of the workday (I LOVE having twins!).
So far the work-from-home thing has been working really well for us. I get the occasional pangs of guilt that I should be spending ALL my time with the kids, but seeing all the creative games they come up with on their own is making me realize that the independent play is just as important for them. I think having an intellectually-challenging job and other adults to talk to is keeping me sane. Plus with a second income I don't have to feel guilty about buying all those educational toys and manipulatives I see on Amazon.