I decided to create a new thread because this is the first final release and has (almost) nothing to do with my first test versions.
AutoRateAccurate
What is it?
This script rates the songs of your library based on informations like Playcounter, DaysInLibrary, PlayedPerDay, LastPlayed and SkipCounter. This way the rating will also be increased if you listened a song with your portable player like ipod!
And it is really easy to use: Normally you only have to enable AutoRateAccurate in the MediaMonkey-Options.
Features:
The script does al lot more than just rating the files:
-Autocalibration
This is one of the mainfeatures of AutoRateAccurate. It calibrates automatically the rating-algorithm so that you never get too much high rated or too much low rated songs. In the Options you can decide how much percent of your library should have five stars and then automatically the algortihm gets adjusted. AND: If you don't want the script to give some ratings, for example half star, just set that value to 0%, like in the screenshot.
This Autocalibration takes about 3 seconds here and can be started automatically on startup of MediaMonkey, which is optional but recommended.
-KeepManualRatings
One of the importants thing for me was to create a script which doesn't need any Custom-fields or other field for additional informations and doesn't overwrite ratings you set yourself. This two options can be activated or deactivated and are very useful if you also want to rate your songs. Also users of portable mp3-players like ipod who rate with the player don't have to fear that their ratings get over-written.
-SkipDetection
This features ckecks if a song has benn skipped. If yes it will update the SkipCounter which is saved in the ratings-field but in a way it is not visible. This skipcounter will also have an influence on the rating of the song, because skipped songs are probably not so good songs. This feature can also be deactivated in a very easy way: Over the MediaMonkey-Menubar. So you only have to click in the SD-icon (looks not so nice yet, I know...) and then the SkipDetection is active or inactive. This is useful if you search a song or want to use a script like "SongPreviewer".
By the way although a skip is only counted if at least ten seconds and at most 80% of the song have been played. This values can be changed in the ini-file. I think there's no need for changing this through the optionsheet since the default values work well in most cases.
Downloads:
Not available anymore. Click here to download new version 2.x.
Comments:
After about 50 hours of programming/scripting and 2 complete rewrites of the code this version should finally be stable. Here it works great and I saw no problem so far. Although it could happen that you existent ratings get overwritten or messed up. So don't blame me afterwards!

If you discover a bug, please post it here or write a PM.
Changes:
-Version 1.01 (27/05/2006)
First Public Release
-Version 1.02 (27/05/2006)
Fixed: Custom1-Field got overwritten (forgotten line from my debug version)
-Version 1.03 (28/05/2006)
Fixed: SkipDetection didn't work under some circumstances
Fixed: Crash if Skip>Playcounter
Fixed: Ratings sometimes too low
-Version 1.1 (05/06/2006)
Added: "Reset SkipCounter" option
Added: "SkipCalculation" option (so you can disable the Skip-Feature completely)
Fixed: Different stability bugs
Fixed: Minor bugs
Fixed: Grammer in OptionSheet

Changed: SkipCounter
-Version 1.11 (21/06/2006)
Changed: Huge speed increase of the Update Library function
-Version 1.2 (25/06/2006)
Changed: Speed improved again
Changed: New icons
-Version 1.5 (08/09/2006)
Added: New "AutoRate now!"-button which recalculates the ratings of all your songs. (Requested by Spazz)
Added: Different "tools" to reset SkipCounter, delete AutoRateAccurate ratings or all ratings. Available in the options under "more".
Added: ProgressBar which shows the progress if you autorate the whole library.
Added: A information at the first startup and more tooltips which describe the different options.
Fixed: Uninstall deleted the whole MediaMonkey-folder.
Fixed: If you played a song before configurating AutoRateAccurate you got an error. (Probably your problem, Sgrom)
Changed: Minor improvements and code cleanup.
-Version 1.6 (29/10/2006)
Added: Confirmations on the "more"-functions. (Thanks kanski)
Added: Function to update tags. Useful for iPod-users. (Thanks BerniPi)
Changed: Improved SkipDetection&SkipCounter for a more accurate rating of "bad" songs.
Fixed: MinSkip didn't work correctly for songs with PlayCounter=0. (Thanks kanski)
Fixed: Crash with fresh database.
Fixed: Some minor (but important) bugs and interface problems.
-Version 1.61 (10/11/2006)
Removed: BrowseByArt-Check. The issue with SkipDetection has been solved so it's useless now.
Changed: "Save changes to tags" renamed to "Rewrite tags". (Thanks TJOHO)
Have fun!

Big_Berny