October 11 is National Coming Out Day when people of all sexual orientations are encouraged to come out and live openly.
(Obviously this has more significance for LGBT folks, but straight allies are included in this. Sometimes in predominantly gay situations it can be difficult for straight folks to admit to being not gay. The whole point is one of acceptance for everyone and acknowledgment of our diversity.)
(And Ally Week is coming up, Oct 18-22, BTW!)
While being gay doesn't have quite the stigma it used to, there still isn't true acceptance and equality. And considering how hard it can be to be gay today, it's that much harder to be bi, or trans, or even LGBT within another minority group like people of color. It can be hard to be unsure and questioning, wondering about your sexuality.
Coming out is a process, and there is no right or wrong way to do it. It's a wholly personal thing, and it can be a lifelong process. It's also a continuum - you may be out to your family, but you may be closeted at work, or at the gym, or at your kid's school, or standing in line at the bank.
The most important thing is to take a step today, in a conscious way. Do something that feels safe to you, but still do something to come or be out of the closet, or even just give some more visibility to all or part of the community. You can talk about your partner, the gay contestant on a reality show, the HIV/AIDS epidemic, your going to Pride, your BDSM leather club, or whatever!
Sexual orientation and gender identity are aspects of who we are, but they do not completely define us. Still, the only way to make progress is to be honest - prejudice and bigotry are based in ignorance, and the more of that we can take away, the less discrimination there will be.
Coming Out Day is actually celebrated internationally. In the US, HRC provides many resources and activities. Here's a handy map for organized events: