What’s the digital version of carving your initials in a tree or writing a message on a wall? In other words, how do mobile users leave a lasting sign of their presence, that says “I was here?” Newly launched LeaveOn is a mobile app born out of a Verona, Italy advertising agency that allows modern travelers to leave text and photo messages digitally across the world…forever! — or as long as this nascent platform stays solvent.

In most cases, these messages, called “balloons,” are viewable publicly for anyone that should find themselves in the same location. For anyone wanting to memorialize the location of an epic adventure or romantic tryst, LeaveOn is their virtual pocket knife or felt-tipped pen.

Communication through LeaveOn is purely unidirectional. There’s no option to reply, like, share, or tag other people’s messages. This is just as well, given that the purpose is to document one’s presence in certain locations. Messages in each location are sorted reverse-chronologically by default, but visitors can search through all past balloons based on user, keyword, or date.

The real question is, does the world have room for another network — another platform to check into? The most technical among us likely suffer from check-in app saturation as it is, while the coming wave of smartphone adopters may be more open to LeaveOn’s travel documenting charm. As PandoDaily managing editor Nathan Pensky astutely pointed out, “It seems to be capitalizing on the whimsy of it all, but how does whimsy scale? It just occurs to me that little cute things like this seem cooler when they’re suuuuper small, and not all pervasive.”

Giving the upstart platform the benefit of the doubt, the follow-on question is, can such a platform be monetized?

Founder Deny Cadorini, believes the answer to the monetization question and that of market need are a resounding yes — and as a founder, he should put forth a confident front. That said, he’s staying mum at this point about future plans for monetization. He claims some unique ideas, while replying with a shocked “OH NO!” when I asked about plans to serve ads. Without ads or a direct commerce tie-in, LeaveOn is going to face an uphill climb to generate revenue.

LeaveOn allows users to follow friends, although the platform is fully synchronous, meaning it requires users to accept follow requests and follow one another mutually. Users can invite friends that they follow on Facebook or by email, although the platform deliberately avoids Facebook Connect for fear of excess virality reducing the personal charm of the experience. Once linked up, followers can then view each other’s various balloons without having to be in the location they were left.

One of the more interesting uses of LeaveOn is the option to leave personal and private messages for friends. The message recipient gets a notification of the awaiting message but, in this case, needs to go to the location to receive it. Sounds like a great way to stage a fun or romantic scavenger hunt. (Heads up to any marriage proposers out there.)

The goal for LeaveOn isn’t to have users check into restaurants and recommend a favorite appetizer. It’s to memorialize special moments and locations long into the future. Anyone who’s ever stumbled upon an old worn message from a previous visitor to a location appreciates the instant connection it builds. “I’m not the only one who’s appreciated this amazing place,” is a natural reaction.

This is a novel concept so far as its the only app to have such a pure use case. Foursquare, Instagram, and to a certain degree Yelp allow users to leave geo-tagged messages and photos in a given location but they lack the impact and emotional purity of a message carved into a bench somewhere.

The service which launched in private beta in March is now available to the public in the iTunes and Google Play marketplaces. The company offers a Web platform as well, where friends can view one another’s balloons.

We’re still in the early days, and with under 1,000 users the chance of serendipitously encountering a waiting balloon are low in most places. By comparison, Kevin Rose’s pet check-in app Oink grabbed 100,000 downloads in its first three weeks after its launch in November 2011,  showing that people were at that point at least open to trying new things — it eventually shut down after failing to maintain traction. Keeping fickle mobile users engaged is the real challenge.

We’ll see if Cadorini’s personal passion project catches on and whether he’s willing to continue bootstrapping it until it does. Personally, I like the old world charm meets modern digital tools aspect of LeaveOn and will be leaving my fair share of balloons during my travels.

[A LeaveOn demo video is available here.]

[Image source, Jono Rotten, Flickr]