It's been a while since I reviewed my bookmarklets and since Carl T. Holscher was doing his, I thought I would list mine.

• Markdown Blockquote (bookmarklet) - A recent addition to my bookmarklets collection is the markdown pull quote grabber. I've recently taken a leaf out of John Gruber's blog and started including quotes from posts that I am linking too. This was quite a convoluted task in the past. Grabbing the link and quote, pasting it in and adding the author and title. Using this bookmarklet though makes the process much more easier. In the near future I plan to modify this so that it renders a blockquote in the format that I use for my blog. Special thanks goes to @malanowski who is the author of this.
• Markdown Page (bookmarklet) - I frequently copy whole pages as reference material. Mostly articles on web development and programming. As I prefer to use Markdown documents, I needed something that converted a whole page to Markdown. This bookmarklet does exactly that.
• Markdown Link (bookmarklet) - I'm grabbing links all the time from Firefox and just about everytime I reach for this bookmarklet. I simply need to click this bookmarklet and I get a markdown version of the link to paste into my document.
• Subscribe with Feedbin (bookmarklet) - I use Feedbin as my preferred RSS reader. In a world of streaming posts and updates on all the social networks, I'm glad there's still a way of subscribing to a site's content without having to succumb to just being another follower. This bookmarklet lets me subscribe quickly to any site that contains a valid RSS feed.
• Save to Instapaper (bookmarklet) - Finally there's Instapaper's bookmarklet for saving articles to your reading list. I use Instapaper on a daily basis for queing up what I want to read later on. Click to the page you want to save, click the bookmarklet, job done.

Bookmarklets are a good way of manipulating the pages on your web browser without installing add-ons. Unless you're familiar with JavaScript though, you will have to contend yourself with finding bookmarklets that others have made. With a bit practice though you could start writing your own.