There are countless websites for writers, and many of them are very good. Here are three which other writers have recommended to me, and I have found useful myself.

First, Writers Services is extremely comprehensive. It has links to almost everything you could want as a writer, from lists of agents to info about printing your own book, podcasting and even checking online security. I'm always referring to it.

Second, Preditors and Editors lists agents and editors, like so many other sites, but the great thing about them is that they recommend or (more importantly) DO NOT RECOMMEND certain publishers and agents. There is nothing subjective about it - the criteria are strict, require documentary proof and include things like non payment, unethical behaviour, etc.

Thirdly for non fiction writers, there's no over emphasising the value of a "hook" for your book or your article. The place to go is Ideas4Writers which also has all kinds of other bright ideas to help you think up great stories and conquer writers block.