The visible bra is becoming more and more prevalent in fashion, and I have to say that I like it. With this trend, there is definitely a fine line between classy and trashy, but as long as you stay on the right side of the line, you are good to go.
Some may say that it's inappropriate to show underwear, but to them I want to point out that the t-shirt was considered underwear (and inappropriate to show in public) until style leaders like James Dean broke the rules and therefor changed them.
The original sexy
So if you are ready to change the rules, consider taking part in this trent. Though allow me to remind you of the obvious: that like the t-shirt visible bras will probably never be a suitable look for the workplace. (Nothing fun ever is.) :(
Since my bosom is already big enough to catch a little more attention that I always want, I like to embrace this trend in a subtle way with a black bra under a sheer-ish t-shirt. Or, if I go more sheer with it, I add a blazer to keep the look smart. But if you as less well endowed, you can go a little bolder without looking promiscuous. Take your cues from Jane Aldridge of Sea of Shoes, who keeps this sexy trend looking demure, by pairing her visible bra with a longer skirt and boots. (Remember that it's always smart to show off either your bosom or your legs, never both in one look.) The ruffles down the front even add additional coverage.