Or just want to create a certain space that shuts off the outside world? I have mainland which can be very messy round about my place. I have tried screens - solid ones are just too flat to look nice and one with any transparancy can affect other items such as trees or windows etc because of the alpha issues on SL.
So I was really delighted to find some stunning sim border creations by FelixvonKotwitz Alter on xstreet. I TP'd over to his place and I was even more pleased when I saw his work in world (pictures can not do it justice)
I bought a set of 16 sculpted mountains with trees, flowers, waterfalls, bridges, sunbeams, little house dooors set into rocks, staircases - and I could go on there is so much in them! THe highest prim piece is 7 prims!!!!! Yes only 7 (I can hardly believe it). They are 20x20x3 and all copy and the whole set was only $795L
Here are some pictures - but do go look in world http://slurl.com/secondlife/Landscaping%20by%20Felix/26/217/21 as it looks much better up close - oh and there are are couple of free gifts out on the sim too ;)