Grammar: 'About.com' Irregular Verbs
Common irregular verbs plus some of the more uncommn ones. Useful for both reference and revision.
[http://spanish.about.com/]
Grammar: A Free Online Tutorial
More than 70 different lessons covering grammar, vocabulary, and written and oral exercises.
[http://www.studyspanish.com/]
Grammar: Lingolex
From Beginner to Intermediate there are activities for everyone.
[http://www.lingolex.com/]
Grammar: Linguaweb
Complete language resource centre. Additionally there is a GCSE revision section.
[http://www.linguaweb.ndirect.co.uk/]
Grammar: 'Parlo.com'
Teaching Spanish through 'Virtual immersion'. A useful site.
[http://www.parlo.com/]
Grammar: Spanish Activities
20 Spanish activities created by different authors. A fun way to learn Spanish.
[http://www.quia.com/]