Oh man do I know where you are coming from (except I don't work and I have one less child). 
On my blog I have a post about a BABYSITTING CO-OP. Do you have friends who might be willing to switch out babysitting? If so, this post will help give you ideas on how to make it run smoothly.
 
Other things I do to get mom time: I go to MOPs (Mothers of PreSchoolers) and I go to a mom's group from meetup.com . My children are at the meetups with me but they are generally interacting with other kids so I have a chance to talk to grown-ups.
 
If your hubby is home at night, could you sneak out to a late movie or to do grocery shopping?
 
If your hubby IS home, I also have some in-home date ideas :)
 
Please feel free to contact me and discuss other ideas. I'd love to hear your thoughts as well.
 
Good luck,
Reagan
whereisthemeinmommy@gmail.com