OperaGame

OperaGame is a user javascript for Opera browser, much similar to the frequently used Foxgame (technically it works more like greasemonkey). It has almost all features as Foxgame, and brings some new stuff also.

OperaGame can calculate server lag so it's much easier to phalanx someone. When your fleet gets phalanxed, it is possible to escape within 4 seconds - you can set your target planet and fleet, and then just press "next" and you're safe.
However, there is one downside - this script is not allowed. I'm not sure why it's illegal, but my bet would be because of the phalanx escape thing I just described.

There's a number of other useful features, such as highlighting debris fields, coloring alliance players or enemy players in galaxy view, showing finishing time for buildings or research, coloring circular or private messages and more.

Whether or not you can be caught with this is beyond my knowledge. I've seen people on banlist before for using OperaGame, but how exactly they got caught I don't know. If you move your fleet within 6 seconds, it is likely you will get banned if reported by your attacker. Other than that, I don't know if GO's can track what browser plugins you use. I do know, thanks to a certain visitor, that Firefox extensions can be tracked. It might help if you set Opera to identify as Firefox or Internet Explorer to websites: Tools > Quick preferences > Edit site preferences > Network > Browser identification.
I'd recommend using this on your multiaccount only.

You can download OperaGame from the official forum (there's an english section if you need help), and while you're there check out some other cool related stuff such as translations to other languages.
If you need help with installing the script, or you want to learn more about Opera's user javascript, visit Opera Wiki.

AutoIt

I won't write much about AutoIt since it's pretty much self explanatory.

AutoIt v3 is a freeware BASIC-like scripting language designed for automating the Windows GUI and general scripting. It uses a combination of simulated keystrokes, mouse movement and window/control manipulation in order to automate tasks in a way not possible or reliable with other languages (e.g. VBScript and SendKeys). AutoIt is also very small, self-contained and will run on 95, 98, ME, NT4, 2000, XP, 2003 out of the box with no annoying "runtimes" required! You can even make compiled executable scripts that can run without AutoIt being installed!

AutoIt can:

• Provide a general-purpose scripting language for all Windows versions
• Simulate keystrokes (supports most keyboard layouts)
• Simulate mouse movements and clicks
• Move, resize and manipulate windows
• Interact directly with "controls" on a window (set/get text from edit controls, check boxes and radio buttons, select items in drop-down lists, etc.)
• Create complex user interfaces (GUIs)
• Work with the clipboard to cut/paste text items
• Provide a scriptable RunAs function for Windows 2000/XP/2003

It comes with an excellent documentation in russian, german, spanish, italian, and of course english. And if you get stuck you can easily get help on the forum.
AutoIt is free to download, and also features a script editor to help you write your own scripts.

OGame Spy Report Beautifier

This script is not published on userscripts.org, at least I haven't found it yet.
I'm still thinking whether to use it or not, since I play for 10 months now I can pretty much estimate how many cargos I need. It takes a day or two to get used to it, but it can be useful in times.
Anyway, the script adds the required number of cargo ships to steal resources in a spy report. You need Greasemonkey to use it.
Although it is written in portugese, you can just change the source of the script to say "small cargos" and "large cargos" in english, or any other language (I don't think the author will mind if you do ;) ).
To do that, open Greasemonkey options - either right-click on the icon in status bar, or go to Tools > Add-ons > Greasemonkey > Options. Then find Ogame Cargos Calc., and click on edit. A dialog opens, asking you to find the program you want to edit it with - WordPad (not Word) will be fine, Notepad might mess things up. When you have it opened, change the following to whatever you want:

• Cargueiros Necessarios - Cargos necesarry

• Cargueiros Pequenos - Small cargos

• Cargueiros Grandes - Awesome huge slow cargos

And save. That should do the trick.
The author claims this script works only on portugese ogame, although it worked for me on ogame.ba. I'll try later today on ogame.org, I need a few hundred deuterium for combustion drive, in order to be able to spy someone. Any offers?
You can check the authors blog for more info and a link to install the script.

Thanks for the mail ;)

Later update: works on ogame.org

More update: seems it doesn't work on .org. Showing zero cargos required.

One more update: the script is updated to work with ogame.org

Automate data input in GalaxyTool

It is mentioned in the post about SheepPro that automated tools are illegal from Gameforge's point of view, so I suggest you be careful when using this. Use your multiaccount not your main account.
You probably won't get caught, unless you update 10 times a day - but nevertheless don't say I didn't warn you.
The script is called OGame Galaxy Return 2, and you need Greasemonkey to use it.
You could always just manually fill your Galaxytool, but there's no fun in that.

Greasemonkey

Greasemonkey, also known as grees@ is yet another usefull Firefox extension.
Here's a description from official Greasemonkey site:

Greasemonkey is a Firefox extension which lets you to add bits of DHTML ("user scripts") to any web page to change its behavior. In much the same way that user CSS lets you take control of a web page's style, user scripts let you easily control any aspect of a web page's design or interaction.

You can install Greasemonkey from this page!

What we are interested here is, how can it improve your Ogaming.
Most common uses (scripts) are:

• Directly send recycler, spy a planet or moon from galaxy
• Removes commander ad, and other ads
• Removes Commander info from left menu
• Show colored alliances in galaxy panel, variable size of debris field icon, adds arrival time to flights overview...

You can download Ogame scripts for Greasemonkey and install them just few clicks. No need to pay for Commander anymore.
If you're a bit advanced user, you can make a custom script yourself and add even more functionality. Diveintogreasemonkey.org can help you with the first steps.

I am unsure whether Greasemonkey is legal or not, you should contact GO's in your universe and ask. But even if it's not legal, there is no way you can be tracked if you use it.