Mongoose Traveller is basically a more modern version of Classic Traveller. The rules are pretty similar (tidied up in places. In terms of setting, I think it's set in 1105 so it's basically another CT clone (with all the CT assumptions in place too).
It's pretty good, if you like Classic Traveller. They've also branched out into many different settings too - there's the default 1105 Third Imperium setting, but they also did several 2000AD setting books (Judge Dredd, Strontium Dog, etc) and Hammers Slammers that use the same rules (but are different universes).
The other big thing about MGT is that they released an SRD of Traveller rules under the OGL. That means third party publishers can release their own material for it - Spica Publishing have released several Career and System Books and also have their own Outer Veil setting, and Jon Brazer Enterprises and Gypsy Knight Games and others have released their own material too.
It's pretty good, if you like Classic Traveller. They've also branched out into many different settings too - there's the default 1105 Third Imperium setting, but they also did several 2000AD setting books (Judge Dredd, Strontium Dog, etc) and Hammers Slammers that use the same rules (but are different universes).
The other big thing about MGT is that they released an SRD of Traveller rules under the OGL. That means third party publishers can release their own material for it - Spica Publishing have released several Career and System Books and also have their own Outer Veil setting, and Jon Brazer Enterprises and Gypsy Knight Games and others have released their own material too.