Lyx, is a word processor and so offers similar functionality to Microsoft Word and Open Office Writer, it however works on a different principle which not only makes things look better, it also makes things easier!
Standard word processors work on a WYSIWYG (What you say is what you get) principle, that is to say that what you see on the screen in front of you is what will be printed, in theory this sounds a good idea, in practice however it means you spend a lot of your time actually formatiing your document (i.e. Bold, Italics, Font Size, Page Layout etc) and so spend less time actually focussing on what you are writing.
Lyx works on a WYSIWYM (What you see is what you mean) principle, that means using Lyx at first seems a little bit strange because it does so much for you, if your writing a paragraph, you tell Lyx thats what your doing and it sets everything for you, tell it you are writing a Title and again it sets everything for you. It also has proper setups for Theses, Articles etc.
The above is a graphical tour of Lyx and should give you an idea of what it is all about. In addition to the great simplicity and beautiful output you get from it (Put it next to a MS Word document to see what I mean!) it also does several other things extremely well:
1) After finishing your writing you can automatically create a contents page with everything done perfectly.
2) If you use bibliographies this is also greatly simplified and much improved.
3) It works using Tex, which is a type setting format, this is especially useful if you are implementing mathematical formulae as it doesn't require any knowledge of Tex inputs but gives you the brilliant output of Tex.
I must say that this is one package that really impressed me when I tried it, it is a small download and worth a try out for anyone who uses a word processor and wants nicer output than they normally get, also excellent if using bibliographies and contents pages as it saves a huge amount of effort doing these manually.
It is worth noting that due to the WYSIWYM principle it does take a small amount of time to get used to, fortunately there is an excellent tutorial located in the help menu to help you get to grips with it.
The package is available on both Linux and Windows