(CNN) -- In your lifetime, you will send thousands, maybe millions of online messages.
But what if you could only send one more?
In China, where superstitions surrounding death are rife, new websites let Internet users leave digital imprints even after they pass away.
One service is called "Life Black Box" and the idea is simple: You sign up and upload whatever you want -- be it secret photos, random thoughts, sensitive files, or final goodbyes. When you die, the website sends your data to people you've chosen.
Li Jia, the creator of the Life Black Box, said he thought of the idea in 2010, when he was on an extremely turbulent plane ride.
"I had recently divorced -- and I realized I had a lot to say to my ex-wife, my son, and my parents," he told China's TechWeb.
Last week, during China's annual Qingming festival to honor deceased ancestors, his website became a trending topic on Chinese social media amid widespread reflection over the missing Malaysia Airlines airliner.
"The Malaysia Airlines incident made us remember life is precious," wrote one microblog user. "If one day, your life is coming to an abrupt end, will you have any regrets? We should create online wills; it's emotional sustenance."
Li said his website now has 360,000 registered users. Many have jobs that are dangerous or require constant traveling, and a great number are in their thirties or forties.
According to TechWeb, over 28,000 online wills have been created in Jiangsu province, where 14 Flight 370 passengers are from.
In another twist, employees at the Life Black Box website said 31 people on the missing jet's passenger list matched the names of its subscribers.
But a spokesperson for the website told CNN no links have been confirmed, as many Chinese people have the same names.
Yet Black Box is not the only Chinese website that attempts to deal with death.
One website called Waheaven, which says it has over three million users, lets users create online memorials by uploading images of their deceased ancestors, after which they can pay traditional tribute by lighting virtual incense or laying virtual flowers.
Another Chinese memorial site calls itself a "virtual home" for dead spirits, and lets users pay blessings to anyone from Princess Diana to Genghis Khan.
But the most melancholy may be the "Last Post" project, by Chinese social media user Lin Dongping.
Since 2011, Lin has run a popular microblog account where he reposts final messages from ordinary people who have passed away.
So far, he has already compiled stories of over 1,500 deaths. After each story, thousands of users, many of them strangers, leave tributes and well wishes in the comments.
A 30-year-old reporter, dying of cancer, wrote in her last tweet, "The operation ended... I couldn't even have porridge or water for six days... this is one of the greatest tortures i have experienced."
Another user posted a suicide note. "I'm depressed, so I'm just going to die. No big reason. Don't care too much. Bye bye."
Over 294,000 people replied, many of them simply saying "Rest in peace."
For today's Internet users, death raises a set of interesting new questions: What happens to our data when we're gone? Will anyone save our imprint, or will our virtual lives fade into digital dust?
Lin said his goal is to honor the memory of the dead, no matter their stories.
"When people die, digital information is their legacy," said Lin in a TEDx talk. "I'm just doing the work of a monk performing a funeral rite."
In the end, services like Life Black Box and "Last Post" seem to say that even in death, we don't have to be alone.
On Lin's microblog, one final post, from a 17-year-old Chinese teen who ultimately died of cancer, was addressed to his younger sister.
"Please remember -- no matter how long you go without hearing from me, I will always give you faith, hope, and love."
CNN's Zoe Li in Hong Kong, and CNN Beijing interns Lucrezia Seu, Qi Zhang, and Andi Wang contributed reporting.