This collection compiled by the University of Leeds, provides you easy access to several corpora (collections of texts) including the British National Corpus, British newspapers and others. It is easy to use and does not require registration.
The largest publicly available corpus of English, available since 2008. It has a database of 400 million words including newspapers, fiction, spoken language and academic writing. You can also search surrounding words to see if a particular word is typically used together with other words (collocation). After using it a couple of times you will be prompted to register, however, registration is free.
GRAMMAR AND PUNCTUATION
Guide to Grammar and Writing - Capital Community College Foundation
A very useful site for grammar problems connected with advanced writing, including punctuation, sequence of tenses, compound nouns and lots more. Also has a selection of links on paragraph level issues, and a link to a related site on essay writing.
Punctuation Made Simple - Gary A. Olson
Worried about whether you need a comma or a semicolon? This site has it all and, as the name suggests, it's clearly and simply explained. It doesn't deal with defining and non-defining clauses, but then you can't have everything.
Ah, the comma. Of all the punctuation marks in English, this one is perhaps the most abused and misused. And it’s no wonder. There are lots of rules about comma usage, and often the factors that determine whether you should use one are quite subtle. But fear not! Below, you’ll find guidance for the trickiest comma questions.
Should I use A, AN or THE? Even after years of studying English, students may find themselves asking that question over and over again. English articles can be quite a challenge. To help every English learner become an articles expert, Englishpage.com has put together the most comprehensive English articles tutorial on the web.
Provided by Manchester University, this resource contains lots of typical phrases you can use in different parts of your papers (without plagiarising). Of course, you can also adapt the phrases you find here to make them your own.
A collection of eight dictionaries and numerous word finding tools, including legal dictionary, computer dictionary, synonyms, related words, homophones and lots more.
Another wide-ranging collection of specialist dictionaries.
This rather interesting resource used to be free - now you can still have a free trial all the time under hard sell.