As ambulances pull up outside Bogota's Hospital Militar in torrential rain, a tousle-haired man in shabby clothes rushes forward, offering patients his umbrella. The cost of a dry walk is 100 pesos (about 10 US cents).
Alvaro Velez is one of an army of impoverished Bogotanos who have an uncanny, entrepreneurial eye for the smallest of money-making opportunities. In a city with nearly 20 percent unemployment, the informal labor market is booming.
Alirio Carvajal chose to set up business in the Parque de Santander - one of Bogota's most favored trysting haunts. He offers poems and songs for sale, and a Polaroid photographing service. He reckons on taking five photos a day. "If I take less, I don't eat," he grumbles.
Mr. Carvajal's background is typical of Bogota's enterprising underclass, many of whom are first or second generation desplazados - refugees from violence and poverty in the countryside.
"My father was killed by paramilitary forces when I was six months old. I left home when I was five and came to Bogota," he explains.
Although he is now confined to a wheelchair, that does not stop him from plying his trade.
Messers Velez and Carvajal have carved out their own niches, but many of their colleagues scrape out a living by offering services the cash-starved city council is unable to provide.
Bogota's streets are riddled with an estimated 4 million potholes, many of them big enough to park a small car in. Jose Rivera, his skin blackened by the hot tar he uses, fills the worst of them. He knows that motorists are anxious to save on suspension parts and will give generously.
He earns about $100 a month - a little over the official minimum wage. Others exploit the shortage of transit police, and spend their days shrouded in exhaust fumes, directing traffic at busy junctions.
The daily downpours which drench the Colombian capital are more than a match for the city's drainage system, and many streets are regularly under a foot of water.
Enter Jose Gomez and his brother, two planks, and four bricks.
For a small fee, Bogota's middle class can use Mr. Gomez's improvised toll bridge and keep their Gucci shoes dry.
As is the case in many developing countries, the list of services is endless. At traffic lights, drivers are bombarded with offers of chest expanders, household items like kitchen notice boards, sets of knives, rowing machines, and anything else hawkers can lay their hands on.
Pedestrians can get their shoes shined, their shopping bundles carried, and have their cars guarded and washed.
But Colombians, it seems, are particularly inventive.
"Given the economic opportunity, we would be a nation of high-flying entrepreneurs," says sociologist Martha Obregon of CINEP, a human rights watchdog organization based in Bogota. "As it is, creativity is simply a question of survival."
For many, hustling is the only option to make ends meet, but Mario Caicedo gave up a "real job" in the sewers to work on the street.
Much to the frustration of bus passengers and public phone users, Bogota suffers from a chronic shortage of small change. So Mr. Caicedo sells customers 800 pesos in coins for a 1,000 peso note. "I earn three times as much, and I smell much better," he says with a grin.
He has been accused of taking advantage of people but Caicedo insists his work is no more than satisfying the principles of supply and demand.
At dusk, Caicedo and his colleagues pack up, and a cavalry of old horses pulling rickety carts emerges to compete with the rush-hour traffic.
At the reins are Bogota's rubbish recyclers, who spend the night sifting through mountains of waste for pieces of cardboard and bits of aluminum.
Whole families turn out to rummage in truly Dickensian squalor.
"Sterling work," environmentalists cry, but the mayor of Bogota, Antanas Mockus, is disparaging. "Many of these people cause more problems than solutions" he says, and, in some cases, he has a point.
Traffic on the city's pitted and congested roads is made worse by a lack of man hole covers.
Iron has a high scrap value, and overzealous recyclers have recycled them all. Mayor Mockus has tried to crack down on informal laborers.
Aside from being illegal, he maintains that they increase crime, reduce business for shopkeepers, and end up costing the city dearly.
"We often spend more putting right the shoddy work of freelancers, than we would attending to the problem ourselves," he argues.
But the mayor has a difficult position to defend.
Members of the public may find the city's unofficial work force unsightly, but they are generally grateful for the services available, and as city ombudsman Alfredo Manrique points out, "To wait for the town hall to carry out public works, is to wait forever."
With 50 percent of Bogotanos living below the poverty line, there is little Mockus can do to prevent ingenious citizens from earning their rice and plantains.