Two footprint systems are wide spread: the "carbon footprint" and the "ecological footprint". Both systems differ from LCA, but both systems can provide extra information on sustainability. Although the name of both footprint systems suggest that they are of a similar nature, it is important to realise that the nature of both systems is quite different.

Carbon Footprint

A Carbon Footprint is "a measure of the impact our activities have on the environment in terms of the amount of greenhouse gases we produce. It is measured in units of carbon dioxide" (definition from In other words: the carbon footprint is simply the amount of kg "CO2 equivalent" emissions.
The system is highly commercialised, and widely spread in business to provide environmental information (in "company environmental reporting").
LCA practitioners can use this information in case they need information on the production phase of a product or service.

Ecological Footprint

The Ecological Footprint is "an estimate of the amount of biologically productive land and sea area needed to regenerate (if possible) the resources a human population consumes, and to absorb and render harmless the corresponding waste, given prevailing technology".
In other words: the ecological footprint is the land (and sea) which is needed to support the life of people in hectares per person.
The ecological footprint is calculated for countries (using statistical information of these countries) and for the inhabitants of that countries. The world average is approx. 1,8 ha/capita (US 9,6 ha/capita, Western Europe and Japan approx 3-5 ha/capita, China 1,6 ha/capita). Unfortunately these calculations are quite complex and not very well defined, so data varies.
The system is widely used by NGOs to make people aware of the impact of their consumption behaviour. The simple "footprint calculators" are giving rapid but far from accurate results.
The strength of the system is that it appeals to the imagination of people.

The importance to LCA is that it provides different (additional) information on sustainability: the issue of land-use in terms of occupation of land.
Integration of ecological footprint data and LCA data is hardly possible. Note that the eco-costs of land has been defined as land-use in terms of conversion of land.