Here is a list of activities you and your kids can do inside the house.
Halloween and fall coloring pictures 
If you have a printer and crayons or markers, you're all set for an inexpensive activity.
If you have a printer and crayons or markers, you're all set for an inexpensive activity.
The following websites (along with about 100 other ones on the web!) have a number of free Halloween coloring pages to print. Under the "Holidays" section, you'll find some Thanksgiving and Halloween pages. You'll find pumpkins, turkeys, pilgrims, autumn leafs... pretty much any fall-themed coloring page you could want!
If you don't find what you are looking for, just "Image Google" the words "Halloween coloring pages" and you'll probably find it!
If you are planning a thanksgiving dinner with a number of kids, you can pre-print 2-3 designs per kid and have the kids' table all ready with markers and crayons.
Halloween Crafts - using their hands
There are about a thousand different fall or Halloween crafts you can do with your kids. Depending on the age of your kids, you can find something that will be interesting and challenging to them.
One thing that is always fun for my toddler is tracing his hands and making something out of it. Here are a few examples that are really easy to do - depending on the age, you might have to help a little or a lot! Decorate for Halloween and Fall
Where younger kids love to help, older ones like to create.
If you have a toddler, get him/her to help you stick things on the windows, put spiders in the webs, draw on paper pumpkins, etc.
For older kids, give them a budget and let them go loose at the dollar store, Michael's (don't forget your 40%-50% coupons!), or any other decorating store. Then step back and let them create - you might be surprised!
Making a center-piece for Thanksgiving dinner
Are you planning on having some guests over for Thanksgiving? If yes, then spend one of those rainy days making a center-piece for the table.
You can go online and choose an elaborate design or simply use candles (or your uncarved pumpkin) and decorate it with leafs, arranged on a platter. Kids can help by making (out of black cardboard) a smiley face for one side and a scary face for the other.
Leaf rubbings
Here's something to do with those leafs the kids picked out when the weather was nicer...
Peel the label off a few crayons (go for fall colors - brown, orange, red, yellow). Place a white sheet of paper on top of a few leafs. Get your kids to rub the crayon horizontally on the paper over the leafs.
Cook / Bake
There are a few recipes out there where kids can help by pouring ingredients or stirring. Give my son a wooden spoon to stir a soup and he's in heaven!
Kids as young as 2 can actively help you when cooking or baking. Just keep them a safe distance from the stove or electric appliances.
Making Leafs Placemats
Take those leafs you picked up a few days/weeks before. Arrange them in different patterns on a sheet of wax paper (leafs on the waxed side). Place another sheet (wax-on-wax) and iron with your clothes iron, on a low setting.
Build a fort
Channel your inner kid and build a fort for your kid(s). Use blankets, boxes, cushions, tents, etc. Get them to help you make it and, why not, have lunch in it with your kids (provided it's big enough!!!).
Whether inside or outside, there is plenty of thing to do with the kids. We just have to stop being an adult for a few hours and take the time to have fun with them!