Big toc/doc tames those massively long tables of content that can sometimes arise on this wiki. Whereas an unmodified TOC will simply put a division between the lead paragraph(s) and the "meat" of the article, using this template will tuck it away neatly on the right-hand side of the page. It is sized to fit seamlessly underneath infoboxes that have pictures sized to 250px. To use, just put immediately after the closing brackets of an infobox and before the first word of the lead. Alternately, if the article has no infobox, just place at before the first word of the lead.
For example:
{|infobox|}{{big toc}}'''Article name''' is . . .
No longer necessary
Its functionality is now a part of our CSS style sheet, and therefore happens automatically. This template should no longer be used in the main namespace — that is, on "regular" articles.
Nevertheless, in other namespaces, you may wish to use this template when you have a page with less than the minimum number of sections to trigger an automatic TOC. This is especially useful in forum conversations, where very long discussions typically have very few sections. If you put {{big toc}} at the top of the forum page, you'll get a bit of navigational help that the system otherwise wouldn't provide.
To reiterate, however, please don't use with normal articles in the main namespace. If an article has only two sections, for example, it doesn't deserve a TOC.