Is it advisable to apply to graduate programs after the deadline has passed? I committed to a decision to attend graduate school starting the semester of Fall 2017. I made this decision around mid-December. I started applications 2 days ago and to my surprise, many of my schools had deadlines of December 15th or January 5th.

I don't feel I badly managed my time. This was just when I felt comfortable committing to this direction in my life. I took the GRE about 5 months ago so that 'future me' wouldn't have to worry about it if I decided to attend. I also saw that some schools had an admission deadline of March 1st, so I figured most universities would follow this pattern it would be ok if I stopped focusing so hard on work and side projects to enjoy the holidays with my loved ones. I'd rather not wait an additional year to attend grad school.

Is it (generally speaking) worth my time and money to apply to these programs so far after the deadlines? Fall 2017 is 8 months away after all. I feel I should still have enough time to get my name into the figurative hat.
You could try contacting the graduate administrator for programs you wanted to apply to, and ask them if it is too late to apply. I would consider doing this before I'd start throwing hundreds of dollars in applications to programs who wouldn't consider my app at all, anyway. However, most programs I've dealt with have online applications that are all marked as closed and won't allow any new applications, even if you wanted to apply, if it is after the selection date.

I don't personally know anyone who has tried this, but I suppose the most it will cost you is a polite email.

In all honesty though, I really don't expect anything other than a "you are welcomed to apply next year" response. A few graduate programs with deadlines in December have already made their decisions, some have contacted students for interviews, and some haven't started reviewing files (but admissions has still been processing their files, ensuring everything is attached, etc). Those that haven't started may still not allow any new applications.

You can ask, but most likely you will need to consider alternative plans, such as looking at programs that have spring admissions, dates that haven't passed, or just waiting until fall of 2017 to apply for fall of 2018. Good luck, regardless!