If you've been assuming that you don't really need an estate plan because you don't have any children to leave an estate to, it's time to reconsider that stance. Creating an estate plan is two-fold — it not only allows you to determine who will get your possessions after you pass on, and it allows you to make your end-of-life wishes known.
No matter what you have to your name, it will go to someone when you die. If you do not have heirs or loved ones you want to leave your estate to, you may consider leaving it to a charity that does work you value. In the absence of any heir in the proper line of succession, your estate will go to the government by default. You can almost certainly think of someone or some cause that you would rather see blessed with your earthly possessions other than the government.
Beyond this, however, you can use your estate plan to dictate your end-of-life wishes, and to establish who should be responsible for ensuring that they are carried out. For instance, even if you have no heirs to leave an estate to, or even no estate to effectively leave, let's say that you have always dreamt of having your ashes scattered in a lake that you spent weekends on as a child. Without proper documentation of your wishes, this is unlikely to happen, no matter how much you wish it.
Ultimately, every person should have some sort of will or estate plan; otherwise, his or her estate and the manner in which he or she is remembered will be up to a complex bureaucracy that neither knows you or cares about your wishes. If you are ready to establish your estate plan, no matter what it may be, an experienced lawyer can help you create the right document for your needs.