The number of maths blogs has risen dramatically in the last year, I am delighted to say. It started just a few years ago when Isabel’s math blog was one of the few (though sadly it has now vanished) to today when we there are thousands out there. Whether it is undergraduates blogging like Me Or My Maths, postgrads like Gooseania or professor (in the British sense so higher status than a lecturer) at Mathematics under the Microscope, all at Manchester University.
There are blogs like NeverEndingBooks which covers advanced topics like Noncommutative Geometry as well as being in the forefront of technical innovations (he is currently converting to using MathML and has a command line version which is fascinating). Then there are large collections of maths related blogs such as those at Art of Problem Solving and the huge number of blogs by Warwick University students and staff at Warwick Blogs.
Many such blogs deal with the writer’s experiences but if it is mathematics you are after then a good place to start is at Carnival of Mathematics: Inaugural Edition. This has links to mathematics blogs at all levels, such as mathematics quotes, mathematical objects like Klein bottles that you can buy, a hotly debated probability paradox (well worth reading for an insight into the intricacies of this subject) all the way up to group cohomology. Do visit Carnival of Mathematics: Inaugural Edition – you may never have time to read anything else once you’ve explored the links and the links to the links …