Melting

Many artificial rope fibers will melt, which can be used as a quick and dirty way to prevent unraveling. Cutting rope with a hot knife can accomplish this in a single step. However, melted rope ends tend to have sharp bits, making them not safe for bondage use (you don't want to get one in the eye).

Braided rope can sometimes be carefully melted a bit (e.g. over a candle) all the way around not at the end, but a couple centimeters up; this avoids any sharp bits, but can be finicky to get right.

Heat-shrink Tubing

A very fast and secure way to finish any heat-tolerant rope is to get some heat-shrink tubing and a heat gun. Pay attention that some heat-shrink tubing has a heat-activated glue on the inside, which makes it much more secure, but can also produce some sticky residue at the edges.

In general, this is not a very attractive-looking solution, but it's very efficient.

Liquid Options

I've also heard of people using tool dip or even nail polish to finish rope ends; I haven't seen the results, but these seem like they'd be too much hassle to be a good tradeoff.