Hi K.,
My sons are nearly 3 (this month) and 15 months (today).
My 3 year old loves cars. He loves duplo legos. He loves to read books. Playdough is a huge hit these days too. He also loves his train table. He likes to sing songs together. Little people are great. Balls are OK for inside as long as they are soft.
I try to participate in some of these activities every day. I always read with him, and try to sit down on the floor and play with him at least once in the morning, and once after nap for about 15 or 30 minutes at at time. Sometimes just me singing along with a CD while he plays nearby is enough interaction for him, sometimes he needs more direct attention and I need to sit down and drive cars around with him. It is boring (yes, I admit it) but he loves it so I do it for him.
We also take an ECFE class together, where we spend an hour a week 1 on 1 singing, doing activities (planned by staff) and crafts.
My 1 year old wants to play everything the older one does :) I try to help him as much as I can. He also just loves to crawl over me, be chased, sung to, bounced on my knee while I sing the William Tell song. He will play independently for about 20 minutes at the most.
The two of them have gotten so that they can actually play together for about 15 minutes at a time. My 3 year old can play independently for about 30-45 minutes without checking in with me. Some activities hold his attention for up to an hour (play dough especially).
It often only takes 15 minutes of me playing with my older son, and then telling him, "OK, Mommy needs to (make dinner, do laundry, clean up, etc.) in 1 minute" and that will tide him over on attention for at least 45 minutes.
Spring is coming!! Once it is warm, you can go in the yard (sandbox?), "work" in your flower gardens (or potted plants), go to the park, go for a walk, look at bugs, watch birds in your yard, pretend to be airplanes, ride trikes (or bikes or whatever you have). I know this time of year is hard, but it won't be long before it warms up.
Good luck to you!
J.
SAHM to Charlie (3-24-05) and Joey (12-4-06)