For example, TechCrunch is great for some of the latest developments in tech companies.
Seriously: The two mistakes I see with people and blogs is (a) spending too much time reading instead of doing, and (b) reading blogs which don't align with their own business, and therefore the advice therein isn't necessarily good FOR THEM (even if awesome for others!), and therefore is perhaps even worse than a waste of time.
Now you can tell I'm being honest because (a) implies you shouldn't read my blog after all!
Here's how you can attack (b). Decide on some fundamental characteristics of your business such as: Bootstrapping or Funding? Wanting to run forever or wanting to sell someday? Wanting to grow large and be the CEO of a 1000-person company or wanting to stay small or even stay single-person? Business model (SaaS, installed, hardware, marketplace, freemium, etc).
Now find bloggers who tend to give advice to the particular type of business you have. This can be difficult sometimes, but at least you have a lens or filter. Some of it is easy, e.g. 37signals and Joel Spolsky is about bootstrapping and staying small but profitable, whereas Ben Horowitz and Paul Graham are about getting huge with funding on online high-margin tech businesses.
And my blog? Well, you'll just have to read a few hundred articles to figure that out. :-)
Techcrunch is actually not terribly helpful for entrepreneurs, beyond watching trends and the intermittent insight into certain markets.
This is also a tough question to answer, as the list is long.
Start with quibb.com and Startup Edition. Between them you'll get a curated list of worthwhile articles and early stage founders sharing their experiences.
You'll get a lot of answers if you Google your question, so I'll provide you with some other food for thought.
How much time a day do you spend reading, as opposed to doing?
When I was working on my first tech startup, I was young (still am) and thought it was important for me to be "informed on what was going on" so that I "wouldn't look like an idiot" in any conversation I had with a colleague or potential investor or customer.
So I read industry magazines, papers and blogs, all with different views on what was happening in our industry and the rest of the world. In fact, I spent about 1.5 hours a day reading.
And by the time I went to bed, I found I could barely recite one thing. One thing! Facts and stats blurred together. And it was it hard to go in depth on any given thing, because I was trying to absorb so much.
Now I take a different approach.
When I'm solving a problem, I'll Google it. (And often will call or email a teammate/colleague/mentor). The advice is relevant and useful, and I can act on it, so it's always worth my time.
It's a weird concept, but if you think about your brain as a garden, everything you ingest (aka content) affects it's performance. And if you spend 1.5 hours reading interesting but irrelevant and ultimately useless content, you waste time you could be doing other things to improve your ability to grow as an entrepreneur.
You won't miss out.
If there's a global situation or crisis in your industry, chances are it will come up in your Twitter feed (so you won't miss it) or at an event, and you can ask people about it (I also find it more enjoyable to learn in conversation).
I also learned it's okay not to know everything. Even Jim Collins in his book Good To Great acknowledges that the companies that are great don't have access to more information - aka information is not what sets them apart - but how they use that information to make decisions.
Hope that gives you something to think about!