At the Augusto C. Sandino International Airport (the airport in Managua, Nicaragua), I have heard there is a VIP service you can pay for, where an agent will meet you when disembarking from the plane and guide you through the immigration and customs process, or somehow make it easier. How exactly does this VIP service work? What does it cost, how do you sign up, and what does it include?
After emailing the address mentioned by Peter Hahndorf in his answer (email@example.com), I learned the following from "VIP Shift Managers" on duty who answered the emails:
The VIP lounge service costs US$34.50 for adults and US$11.50 for children under 12 years old. Payment is made as you enter the lounge on the day of travel.
The staff in the VIP lounge will take care of the immigration, customs, and airline baggage check procedures. Guests receive a plate of sandwiches, two complementary drinks, Internet access, and cable TV. Departing guests can wait in the VIP lounge until the boarding process begins.
VIP service can be provided for departing or arriving travelers. For arriving travelers, VIP staff will meet you in the jetway with a sign with your name on it. Reservations need to be made (I assume via the email address) with sufficient time for the staff to be able to prepare to receive you and should include the flight date, airline, and flight number.
Arriving travelers using the service fill out the immigration and customs forms as usual on the plane. The VIP staff will turn the forms in to the appropriate place, and if by chance duties are owed they will come to the lounge and let you know. In that case, you can go down and pay them personally, or you can give them the money and they will pay and return with the receipt. They will retrieve your luggage from the baggage carousel and when all the details are finished, they will return to the lounge, return your passport, and let you know everything is ready.
For departing travelers, VIP staff will take care of baggage check-in using the first class line, so it isn't necessary for the traveler to wait in the standard line. However, they still recommend getting to the airport sufficiently early to accommodate any unexpected delays.
Try the VIP service at Managua airport: This service is one of the most unique you may experienced [sic]. You'll be greeted by an Airport representative with your name on a card at the end of the jetway or on the way down the corridor. Hand them your passport, $5, and be escorted past the long customs and baggage pick-up lines into the VIP security entrance. You'll head upstairs to the private lounge, enjoy a cocktail and some snacks while the officials process your passport, customs, secure your luggage and have it curbside with a "watcher." All this for $30 per person. You can make the reservation directly through the website...
However the link they provide does no longer work.
An English page on the Airport site talks a bit about the VIP lounge but not about the whole service. The Spanish version of the page mentions the $30 again but doesn't explain all the services. It does however list a phone number and email address for reservations. You can try to email them and ask for details.
There is also some talk about the service on the Nicaragua Living site, but it doesn't really answer your question.