This blog is great for learning and brushing up on grammar. It posts a lesson on a different grammar rule every day, with sentences to practice that particular rule. It focuses on a different rule every month. I mostly like that it provides a lot of grammar practice, because it can be really hard to find a lot online.
The tags help with finding their posts on various rules, editing mistakes and news in journalism. I personally think that they did a good job tagging their most popular and helpful subjects.
They also have their posts organized into categories, which makes it a little easier to find a post if you're looking for a broader topic than one of the tags may cover.
Grammargeddon is a grammar blog that offers some interesting and funny ways to remember difficult grammar rules. It also finds funny grammar mistakes in newspapers, ads and comics.
This is much more than your average online dictionary. Search for quotes, look up abbreviations, find cultural definitions, look up root words and play grammar games. This site has loads of all around useful resources.
The post with rules on the most current events is always at the top, so it's easy to find. It's a little annoying that there is no way to look at archived posts, but I think the blog might be fairly new.
This is a blog run by editors at Gatehouse Newsroom. The rest of the website has a lot of resources for journalists, but the Editing Words blog is a great resource specifically for editors. They post AP Style rules and tips that pertain to current events, for example, the have a post explaining how to refer to "Obamacare" in stories.
I like this idea of "practicing" verbs. It's not a waste of time to practice accurately describing what you're seeing. Carry a notebook with you and try to absorb something every day.