Recently I was lucky enough to be given, by SQL Server Central, a free copy of Redgate SQL Prompt 3 which is a tool that provides the equivalent of Visual Studio Intellisense for SQL Server Management Studio. Since then I've been evaluating it and thought I'd write a mini-review here. Its actually quite well timed because Redgate are due at the Conchango community day on 2nd February at which they will be showing their wares. Unfortunately I can't be there due to the minor matter of me being 6000 miles away but at least I can get to try SQL Prompt for myself.
The main functionality of SQL Prompt is to present a combo box (which is called the candidate list) to you as you type which shows you all the available objects that you can then type. For example, type FROM followed by a space and it gives you a list of all the tables that could be in the FROM clause. When writing your SELECT clause type the alias of a table followed by a period and get a list of columns in the table. It also makes functions available to you in the candidate list.
That's the base functionality and in that regard it hasn't really changed much since previous versions other than some UI tweaks. As ever though its the nuances of a product on which you make your decision as to whether you should use it or not. I had a copy of SQL Prompt 2 (from before the technology was bought by Redgate) and ended up uninstalling it, mainly because the candidate list took an age to display and in the end just became obtrusive. I haven't experienced the same with SQL Prompt 3. Responsiveness is as good as you need it to be - and its even configurable.
When I first started using it I didn't like the fact that you had to use enter to select an item from the candidate list because I'm used to using TAB to do that in Visual Studio. It turned out to not be a problem though because I found that you can configure that as well - and TAB is an option. Other features that I like are:
autocapitalisation of keywords
suggestions for join conditions based on existing foreign keys or matching column names
inclusion of variables in the candidate list and built-in shortcut codes for generating code snippets
Expansion of * to a column list (that's the wow factor feature - my colleague
Christian Wade who sits next to me was particularly impressed over that one - and hopefully a little bit jealous that he doesnt have it

)
My only complaint (so far) is that when using it yesterday the error dialog below appeared when I clicked the 'New Query' button in SSMS. That was an isolated incident though so fingers crossed it doesn't happen too often. I haven't found a way of submitting bug reports to Redgate (actually I haven't bothered to look) but if they're reading this, the contents of the dialog are attached to this blog post.

In summary, I'm very impressed. I won't be uninstalling this one. This is well worth a measly $195 of your boss's budget.
-Jamie
UPDATE 2007-01-29: I can now reproduce this error on demand. It seemingly only occurs when I run sqlwb.exe as a different user via the RUNAS.EXE command.