First, I have to mention vealcalf2000
- every time I see you post somewhere, I look at your avatar and think 'my goodness she's gorgeous'.
As for indoor pursuits....
I like stairs. Well, not really,
but they're pretty handy for working up an indoor sweat. Step ups, upstairs sprints, the whole up-a-step-down-a-step thing (not sure what that's actually called)....you get the idea.
Burpees are also great (well, again, not really - they kinda suck, but they do what it says on the tin) for getting your blood moving, and you can do them pretty much anywhere.
Um, I won't go into detail on my last idea - but if you have a romantic partner hanging around, they might be able to help you work up a sweat once in a while.
Personally, that's one of my favourite kind of workouts.
Unfortunately, I can relate to your problems with the weather (outside my house is pretty much a skating rink at the moment) and walking. But surely shoveling snow should count for extra!?
'Hope that helps - I'm so impressed by your insistence to stay active despite a great excuse to take a break!