I grew up on a farm 20 miles from the nearest town (not counting a couple of “crossroad communities” that really weren’t towns but just a convenience store and maybe a church or two). We were rarely bored- we watched TV, read a lot, talked a lot, and the family was always good for making its own drama when there was nothing on TV.
Then I lived in Montgomery AL (pop: about 250,000) which can be a frustrating place but not really “small town”. I didn’t live in one of those until I moved to Georgia.
Where, the answer to your question is sort of disappointing:
1- cable TV
2- video (small towns probably have more video rental stores per capita than large cities, and of course netflix)
3- the Internet* is HUGE in small towns- I’ve known more senior citizens in small towns who could qualify as web masters than I have in the cities I’ve lived in
4- dining/drinking
5- driving to big cities for things you can’t get in small towns (shopping, porn, concerts, stage shows, well stocked bookstores, specialized dining [if there are more than 40 people a Chinese place and a Mexican place will materialize from the earth, but if you want Indian or Thai or Cuban or whatever you’ve got to cook it yourself or ride)
6- lakes (most small towns are built near a river/lake/or some other outdoor recreation
I should mention that the towns above had populations of around 20,000 and weren’t the “truly tiny towns”, like Maplesville*. However, going to public school with kids from the teensy tiny communities of rural Alabama, even the ones who were in poverty- if they had a TV- were well up on pop-culture. I doubt that any area of the country ever responded as immediately and radically to TV and radio as the rural “heartland” areas. When I was little my 90+ year old relatives in the middle of nowhere all knew what nights Diff’rent Strokes and Dukes of Hazzard and other shows came on, all watched Johnny Carson, all watched I Love Lucy and Bonanza reruns every afternoon and the news.
Now what they did before cars and electronic media- well, I think that’s one of the big reasons they had 14 kids and relished the opportunity to go to war. 
*Speaking of the Internet, I used to drive through the tiny Alabama hamlet of Maplesville a good bit. (It’s official population 685 but I swear to God they’re counting cemeteries and Cabbage Patch dolls to get that figure.) Pardon the self-reference, but I once described it as a “blathering senile unwashed amputee of a town (a thrift store, a pool parlor, lots of boarded shops, a collapsed but occupied house on its one street that has Christmas tree lights year round, all standing in the shadow of a strangely enormous Baptist church)” and as of the last time I drove through there a few months ago that description stands.
One night I was stopped at a railroad crossing for a couple of minutes and I looked into the house next to the road, a half-collapsed old simple bungalow and it was an image I’ll never forget. Inside the house was dark, but through the window I could see an old woman in a pink bathrobe sitting down surfing the web, with her skinny old man in overalls standing over her shoulder, the computer being the only light. Moreso than anything I’ve ever seen it made me think “If Norman Rockwell were alive today, this is something he’d draw”- just truly made me lament my own lack of artistic ability.