We have family memberships to our local Zoo, science center, and natural history museum. All three are great for toddlers. The Zoo is a warm-weather activity, the other 2 are cold or rainy-day activities.
We typically ask for memberships for holiday/birthday gifts, and our family has been very generous. So they're often "free" for us because someone else has bought the membership, but memberships are not expensive if you consider the amount of use you can get out of them. We have found that we do well with 2 memberships a year: one indoor activity, one outdoor activity. Any more than that, and they don't tend to be as good of a value because we're trying to split our weekends up among too many things. Sometimes you can get discounted memberships or admissions through Groupon or other coupon services/books, and some places have deals where you can get memberships to a number of places for a reduced rate (like Zoo + museum, for example).
If your local institutions have really expensive memberships, check online for other institutions that have reciprocal agreements with them and might have cheaper memberships. You can still get into your local place for free because of the reciprocity program, but without paying the higher membership price. (This is getting more complicated as some institutions get wise to people doing this, so check the fine print before spending any money. We choose to pay the higher price for memberships because we want to support our local programs.)
I've found a wealth of free activities in our city by subscribing to a huge number of local-events email newsletters, and by reading our local entertainment paper (most cities have some kind of free weekly paper that lists upcoming events in the area). When we hear about an event, we put it on our calendar, and if we need an activity that day, we go to that.
Some examples of good events to watch for:
- home tours, block parties, and other neighborhood-based events (sign up for local neighborhood newsletters, not just for your neighborhood, but other neighborhoods near you). Community development organizations frequently have community newsletters like this, as do large institutions like hospitals, universities, etc.
- children's events (watch especially for things like public health fairs, safety events, church-based activities, etc. - these are often well-funded and have plenty of child-friendly things to do)
- farmer's markets (in our area, we have one almost every day of the week in the summer, and usually an indoor one somewhere on winter Saturdays)
- free outdoor music, theatre and dance presentations (there's tons of this in the summer in our area)
- indoor music/theatre/dance can often be free or cheap, too, if you're willing to attend school events -- check local high schools, colleges and arts schools for programming.
- live music at local coffee shops, bookstores, bars or restaurants (we take our toddler to bars for the music, if it's not too late at night -- she loves it! But, we also have a no-smoking law for public places. We wouldn't take her to bars, obviously, if they were full of smoke or rowdy.)
- ethnic festivals - check colleges and churches for these, as well as neighborhoods and larger venues like fairgrounds, etc.
- seasonal or food-based events (i.e., Strawberry or Wine-making or pie-eating festivals)
- church festivals/carnivals
- county fairs
- Renaissance fairs or other re-enactment events
These aren't all free, of course, but an Entertainment Book is a good resource for discounted tickets to bigger events, or watch your email/websites/Groupon for discounts or volunteer opportunities. If you're willing to show up early and blow up balloons or something, sometimes you can get in to the whole event for free -- you just have to know how to sign up. We often do this.
Besides events, other things we do frequently on nice summer weekends:
- take long walks or bike rides in the park (sometimes parks in our neighborhood, or sometimes we drive to other local parks if we want a change of scenery) -- DD does great in a bike trailer
- go shopping at our local market for bread & cheese and have a picnic at the waterfront
- take DD to the playground or somewhere else she can run freely (and fall down safely)
Things we do frequently on rainy/cold weekends:
- go walking at the mall and let DD play in all the kid-centered areas (we don't shop, though; just walk -- otherwise this would be way too expensive of an idea)
- go to the library and let DD play in the toy area while we sit nearby and read books or magazines
- go to the library and check out a fun DVD and watch it together
- go grocery shopping (this is actually a good family activity for us if we stay focused on having fun rather than doing a lot of shopping very quickly. Better early in the day before the crowd hits.)
DH and I both used to volunteer a lot, before DD arrived, and we've had to cut back a lot because most of our volunteer work was at a local homeless drop-in center where the environment is a bit too volatile for us to feel comfortable having our toddler there. However, we've been able to stay committed to a local Books-to-Prisoners program -- DD comes with us and helps us pack up books to send to folks in prison. If we're lucky, she naps on the couch while we're there, because her book-packing can get pretty haphazard and mess up the library quite a lot. :) Something like this might work for you. You could also call organizations you'd like to support and ask if they have family-friendly volunteer opportunities. You might be surprised by what's available.