Online tests
Compleat Lexical Tutor has a sub-homepage for tests. Most of them respect the vocabulary level of the students as a matter of word frequency.
Grammar tests This website contains many grammar tests and some brief feedback is given should you answer incorrectly. It is free to everyone, although for a fee you can access even more of the site.
The Internet Grammar of English is an academic grammar. It deals mainly with with syntax. It is free only to those who log on from a UK address.
Grammar Station is a free service, but you have to register for it. It contains a lot of grammar information with examples sentences that show what is good and bad. It includes a grammar checker which is not very reliable, but it can be useful.
Wordskills Sets of tests and you can have the results emailed to you and your teacher.
Test your English (University of Cambridge)
Not sure which exam is right for you? Test your English with our quick, free online test. It will give you an idea of your English level and tell you which Cambridge ESOL exam might be the most appropriate for you.
Vocabulary based graded dictation test This pdf consists of an article by Paul Nation about this test and examples of these short tests are in the appendix.