nobr - Content does not wrap at end of the line. Same effect as using the CSS property white-space:nowrap; Never standardized, but I believe IE and Netscape supported it.
wbr - Similar to a BR element. This tag indicates that a line of text may be broken at it's location if it's needed, but doesn't neccessarily need to be. Doesn't really have a display value, similar to <br> in that respect. It's an empty element, never standardized, I believe IE and Netscape support it.
multicol - Splits text up into evenly space columns. Attributes:
cols - Number of columns
gutter - Space between columns
width - width of multicol element.
It's a block level element as well, never standardized, Netscape supported it, but I think as of NS 6 support was dropped. I don't think IE supported or supports it, but I may be wrong.
spacer - Gives you whitespace. Never standardized, only supported by Netscape, but I'm pretty sure Netscape 6 dropped support of it.
type = horizontal - horizontal space
= vertical - vertical space
= block - make it a block level element
width - width in pixels
height - height in pixels
size - size of element in pixels. If type is horizontal, it's width, if type is vertical this is height
hope that helps some