You wouldn't think that there would be blogs out there purely dedicated to giving you a daily dose of Excel fun... but there are. Probably more useful for the advanced users who are looking for answers to common problems - beginner's would get far too lost in the Excel geekiness here...!
Andrew Engwirda is a self-proclaimed 'incurable Excel addict' so a crazy amount of blog posts here on common Excel issues. Includes a few downloads as well.
A large Excel 'knowledge base' here. Plenty of categories on the left to easily navigate and try and find the topic you are looking for more help with. Also includes a forum community to ask further questions.
A very detailed blog with step by step guides, VBA codes and recent news.
Focused on charts and VBA programming
A simple website but some interesting Excel info here including a 'fun stuff' section and a good book list.
A very good blog whose author has just set up an online course for further instruction. Includes quite a lot of advanced stuff like Power Pivots.
A good Excel news blog and trouble shooting.