I've had to put my foot down about this recently.
DS loves the Something Special programmes and a nursery rhyme DVD done by the same bloke. He likes a couple of the cbeebies programmes too. And would quite happily watch them ALL day. I found that we had it on more and more during the day and a couple of months ago when he cried because I said he couldn't have a particular DVD on because we were going out, I decided enough was enough!
Now, he watches an hour or so in the morning (depending on what time he wakes up and how tired I still am lol) in our bed and then an hour or so after his dinner (although if it's nice we'll play outside and he'll watch a little bit while he has his bottle). I prefer him to watch his Something Special DVD because it teaches them different signs.
He 'helps' me quite a lot - pulls a chair up to the counter and I let him do the safe things to help with dinner, he'll help me do the dishwasher or washing up (with lots of towels under the sink!), we water the garden, he hoovers with me, do crafty stuff, blocks, cars, trains, go for walks etc... The biggest change has been how much he enjoys helping me with the things I just used to get on with before while the TV was on.
I second pp are there any buses or any groups in walking distance? I find it so much harder to keep DS amused if we're stuck in for the WHOLE day - a walk to the shop or even a quick walk round the block helps to split the day up too.