Thanks to Roy Osherove for this segnalation: Dataset Quick Watch "visualizer" Add-in for VS.Net 2003.
This project allows you to view the contents of a dataset while debugging, just like the “visualizers” in Whidbey (you select the expression, right click it and hit the “Dataset Quick Watch” menu).
Great tool! 
DBDesigner 4 is an interesting (open source and totally FREE) tool for designing your database.
It's a visual database design system that integrates database design, modeling, creation and maintenance into a single, seamless environment.
It combines professional features and a clear and simple user interface to offer the most efficient way to handle your databases.
List of features
- Available on Linux / MS Windows
- User Interfaced based on industry standard layouting software
- Canvas navigation similar to Adobe Illustrator® and Photoshop®
- Palettes (docked / floating) including "Bird Eyes view"
- Available objects include tables, realtions, labels, regions, images
- Extensive Drag'n'drop support
- Extensive Popup-Menu support
- Advanced Editors
- UNLIMITED Undo-/Redo- functions
- Copy-/Cut-/Paste clipboard functions (XML, DDL)
- Align functions
- Design Mode / Query Mode
- Reverse engineering MySQL, Oracle, MSSQL and any ODBC databases
- Userdefined schema-generation
- Model-To-Database syncronisation
- Index support
- Automatic foreign key placement
- Weak entity support
- Standard Inserts storing and sync
- Full documentation capabilities
- Advanced model printing
- Output as image
- All MySQL datatypes with all options
- User defined datatypes
- Database storage, ability to save model within database
- Network-/Multiuser access through database storage
- Version control*
- SQL Query Builder
- SQL Command History
- SQL Command storage within model
- Plugin interface
* Version control only available when using database storage
Wonderful tool! 
Again with the Longhorn Preview...
I agree that it's only a preview and the code is not optimized (presence of lots of debugging code, feature not completed etc.) but... what's this error?
It's not so clear... 
The first thing that comes in my mind during the little evalutation of Longhorn is: will the future applications ready for Longhorn? Will be ready to use all the powerful feature of Longhorn?
I think that this is not a simple question, but a problem that must be well evaluated. Longhorn seems to be a completely revolutionary OS, with features like WinFS and Avalon that we've never seen on the other Microsoft OS.
Ok, to run Longhorn in a good way, a new hardware is required... A Pentium 4 3Ghz with 1 Gb of Ram and ATI radeon 9800 128Mb (my machine) is the minimum I think (the preview version runs quite slow, but I think it could be also because it's only a preview version, so with lots of debug code in it). But the problem is not the hardware (in 2006 there will be lots of machines ready to run Longhorn in a great way and with low price), but the software (expecially the third party software).
I think that writing a program that could work in a good way on a Longhorn System and on an other Windows OS (such as WinXP or Windows Server 2003) could be not so simple... programmers must write Longhorn-only version of these programs? Or how they will push Longhorn-only features in applications that must also support Windows 2003 and XP (or maybe 2000)? It's not so easy...
Not only the OS must evolve, but also the programmers platform. I'm reading about the new Framework 2.0 but... it will be ready to work with WinFS, Avalon and Indigo?
And what about the new driver model for Longhorn? Drivers will be ready?
Longhorn could not be a closed OS, so third party programs must be ready for it... I think that we've to start thinking about this!