A link pyramid is just building a 2nd layer of links to your 1st layer links. Usually the 2nd layer has a lot more.

For example.. build 100 profile links pointing to your money site.. Then build 1000/4000 or however many profile links pointing to only those 100 initial links. You can use any type of links for either layer. A pyramid is just the link structure.

Here's an open linkwheel:
Wordpress article links to your site AND Squidoo article.
Squidoo article links to your site AND hubpages article.
Hubpages article links to your site AND Xanga article.
Xanga links to your site only.

Here's a closed linkwheel:
Wordpress article links to your site AND Squidoo article.
Squidoo article links to your site AND hubpages article.
Hubpages article links to your site AND Xanga article.
Xanga links to your site AND the original Wordpress article.

Again a linkwheel is just a structure and you can do it with any kind of links.