I try to find bits of balance in different ways...
As a mom: Having one of the older kids help me cook dinner, even though help should definitely be in quotes there. Making a conscious effort to do things one-on-one, even when the busy part of my brain wants to be "efficent" and combine activities. Sending e-mails to them during the work day to remind them that I'm thinking of them, and to remind myself that there's more to my life than my work.
As a wife: Taking time away from the computer (and away from the never-ending household chores) to watch a movie and drink wine on the couch with my husband.
As a career-oriented woman: Coming here, definitely! But also taking the time to update my story archive blog, and giving myself permission to not feel guilty about having to work late when I need to. It sounds kind of new-agey, but sometimes I need to tell myself that it's OK to let my husband put the kids to bed, that it's OK to get my work done. JennS, I totally agree -- the guilt is one of my biggest challenges, too.
As myself: A tall glass of whatever strikes my fancy, a very hot bath, a good book, and the understanding that no one is to disturb me while I'm soaking in the bathroom unless they're bleeding. I haven't been interrupted yet!