Because of a favorite rabble rousing desert rat author, a while ago I paraphrased his quote as a sidebar thing on my previous blog theme:
[The Blogosphere] is like a stew. If you don’t stir it up every once in a while then a layer of scum floats to the top.
I just hand coded it into a text widget, and maybe added two more quotes I found about writing that I [reworded] to make it about blogging. Ha ha.
One of my web design projects called for a widget with a testimonial quote; the idea of asking them to hand change it from time to time seemed silly, and those I found the Quotes Collection Plugin.
It’s pretty slick, you just add quotes to the back end:

Adding a quote to the collection.
I am not using the source field, that would let you link. If you used tags you can group quotes.
When I think of it every other leap year, I just do some searching on quotes about writing, then just mod them to my own twisted ways.
You get a widget you can put on your sidebar, change settings to load a random quote. On the front page, I have it so you can page to the next quote, on my page sidebars, it is set to auto-refersh via jQuery.

Sample sidebar quote
And you get a shortcode as well, so I am able to have a page that shows all my quotes, even to make it do random sort each time via putting in my “On Blogging” page:
[quotcoll orderby="random"]
Nothing earth tremoring here or that technically complex, but I really respect a plugin that does exactly what I was looking for (and then a tad more), with a reasonable interface.
Top / Featured Image Credits: That’s a screenshot of my own blog! Get over it, legal hippies.