i love the rubberband thing that was mentioned. i do that to myself while food shopping with the whole family all the time. i take the band off the blueberry or strawberry container and walk around snapping it on my wrist while we are shopping. My Husband/Dom likes to be the one pushing the cart so he sees me doing it and just smirks and whispers to me that i'm such a slut as He sees my eyes roll back in pleasure with every snap. The funny thing is the kids are right there. Granted thy are
3yo and 18mths but they don't notice or just think i'm weird. That is some thing you can have your wife do while she is shopping and people won't think twice about it. People have been doing it for years as a way to quit smoking.
Another thing you can do is if possible call your wife on her lunch break and get her alone whether its her office or the bathroom and make her pinch her nipples or even snap the rubberband on them. When she is done it will leave a lingering pain to remind her of her place.
Personaly i'm an exobitionist so you might try when you are out in public when no one is looking you might cop a feel with a pinch added in or a quick slap of the ass. Doing things in public can get her used to being in the submissive state of mind when you're not around as well. The jewlery idea is good as well. She may not be able to wear a collar at work but a spicific anklet or bracelet or necklace could be a daily reminder of her place.
Create a pet name for her to call her around the house that will also act as an audio reminder as well. It doesn't have to be slut or anything like that. Pick something that you usualy wouldn't call her but wouldn't raise questions from the kids.