.Net Reflector by Lutz Roeder

Recently, I was assigned to implement and test a tool in our company.
I was given only the application output (aspx, dll, no source code), and turned out the output has also been pre-compiled, so that means we were not even able to look at the aspx (all compiled to assemblies by .net).
The purpose of the pre-compilation is mainly for performance, but it is quite useful also when u don't want the client to modify anything to the application, even to the aspx content :P
So at that time, i only have the application output and the database file (luckly they didn't encrypt the stored procedures :P)
Of course, when doing the setup and deployment to our environment, i found a lot of things which are not being covered in the document, such as "what will happen if i click on this button", etc. They were all like in a black box, which i am as a software programmer, always want to know what is the exact process flow detail, so i will be able to answer with confident if there's any question to the application.
This is the time where the Reflector becomes very handy :P
So with the great help of the reflector, i was able to see the logic of the application and find the root cause when i was stuck with the deployment.
I remembered one time several months ago, when i have a small modification which i have to make to a tool, so i was given the source code at that time. But when i finished the modification and deployed to the production, the tool was not working anymore, whereas i was quite sure that the small modification will not cause any failure to the system. So at that time, i did a dummy debug to the application, i put console.writeline every step in the code, until i found that at this certain portion of code / function, the error always happened. So i downloaded the original dll which i have backup earlier (remember, always backup!!) and then i opened the dll with reflector, searched for that part of code / function. And there i found that the code was different compared to the source code which was passed to me :( can you imagine how frustated i will be, if i didn't use this tool? So i sent the explanation to my project manager and he's ok with that since i also showed him the comparison proof that i was given not the latest source code of the tool :) so thanks so much again to Lutz Roeder's Reflector :)

You can find the tool with other very useful tool in Lutz Roeder's site : http://www.aisto.com/roeder/dotnet/

So i always have these several tools when doing the programming, such as :
1. EditPlus : very handy for editing text, regex plus syntax templates for c#, javascript, sql, etc
2. Araxis Merge : compare files and folders, very very useful especially you have several environments (development, testing / staging, production)
3. .Net Reflector : as mentioned above.
4. SnagIt : Image capture tool, very fast and handy when doing screen captures for documentation, etc

For more very useful tools when doing the programming, there are several good articles such as :
James Avery : http://msdn.microsoft.com/msdnmag/issues/04/07/MustHaveTools/
Scott Hanselman : http://www.hanselman.com/blog/MyGrokTalkTenToolsInTenMinutes.aspx