I thought I would start the actual substantive posting (i.e., posting wherein I actually recommend/review online resources, rather than just stand on a soapbox) with a few online dictionaries. These are by no means the most important sites you’ll ever use to learn Hebrew, but they’ll be with you as tools to help with all the rest.
First, Google Translate:
This is a semi-decent online translator that can be used to go back and forth between English and Hebrew (along with dozens of other languages, thanks Google!). The main advantage of this particular site is that it can translate whole sentences or paragraphs. The main disadvantage of this particular site is that it can translate whole sentences or paragraphs wrong. There is a lot more work involved in ensuring that everything in your sentence(s) is grammatically correct and matching for gender, number, etc.
This is an Israel-based online dictionary (hence the .co.il web address), and it has always served me well. It has some of the same issues as Google Translate in terms of the amount of work that it often takes to get correct and appropriate answers, but it has what I consider to be several advantages over Google. First, all of the Hebrew terms include the nikudot (vowel markings), which means you’ll know exactly how to pronounce your new word; Google provides only the unmarked text. Second, Morfix is fantastic for when you’re reading and come across an unfamiliar word, but can’t figure out which parts might be prefixes or suffixes, and which part is the actual word. On Morfix, just enter the whole term as it appears, and it’ll give you all of the possibilities. This still means, of course, that you have to think a little bit to figure out which one makes sense in the context of your reading, but that’s nothing new. Third, a new feature allows for the translation of short sentences via Google Translate, filling a need that had been missed, and ensuring that I never have to use Google Translate ever again.
Lastly, and this will only be of use for iPhone users, Morfix has the only consistently reliable free app (that I’ve personally found) for translating Heb-Eng and vice versa. You’ll need to be connected to the 3G network, but not the wireless. As an added bonus, both the website and the app have the option to search on Wikipedia, which I’ve often needed to do to figure out just what a term means (e.g., last week I needed to look up an acronym; Morfix told me that it meant something along the lines of “general manager/CEO/etc”, but that didn’t really help me figure out what the text was saying, so I was able to use the link to Wikipedia to look it up and figure out a more precise meaning for the term).
This particular dictionary, as is obvious from the name, will only be of use for some of you. I found it particularly interesting/useful as a student of Arabic when I was trying to make connections between the new things I was learning in Arabic and the things I already knew in Hebrew. The main two things to note for this dictionary are these: 1) it gives you not only the word you’re looking for, but in the case of verbs, gives you the appropriate preposition (something that I’ve seen in only one other dictionary, which is only in book form), and 2) it allows you to search either by whole word or just by the root. It can be a bit cumbersome to use and take a while to get used to, but it can be worth the effort you put in.