Would be interesting to find out what sites you are using in your language learning, what resources and so forth?
For my it's mainly
SE/HR: http://lexin.nada.kth.se/sve-kro.html
EN/HR: http://www.eudict.org
and then I use for words the great Mac OS X program ProVoc: http://www.arizona-software.ch/provoc/
and then I get a lot of material from the Croaticum course I am taking now in Zagreb so I am not yet in need of grammar exercises and material on the internet, but I will in one month from now.
What do you guys use? Is anyone using the UniLang site? I've noticed that the hole/rupa-exercises to decline the cases are actually really really simple to us to implement new exercises. Is anyone using that?
Also I haven't used it as much but it looks good for language understanding exercising: http://gloss.lingnet.org/searchResources.aspx