In my house there are six or seven different devices (5th gen iPod, Nokia 5310, microSD cards, USB thumb drives, wife's Xperia, ...), which I sync frequently, using MM (obviously!). As I wanted all my devices displaying the CORRECT device images, I dug the Internet searching for hi-res images and edited then all to create MM friendly transparent PNG versions.
The result is here, for your pleasure:
As I found it funny, I just searched for other well known devices and also created device images for them. Now I'm sharing all the device images I've created, so you all can benefit. If you want other well known devices added to this gallery, just let me know. I'll find a good resource image, edit it appropriately and publish here.
Apple devices
* iTunes icons are intended to use along with MediaMonkey iTunes plugin
Android devices - Nexus
Android devices - Samsung
Android devices - Motorola
Android devices - Sony
Android devices - LG
Android devices - HTC
Nokia devices
Sansa Media Players
Creative Zen Media Players
Other Devices
USB thumb drives
Memory cards
How to use:
1) Right click the desired image and choose "Save image as..."
2) Save the image in any location you want. If you have admin permissions, you can choose to save in the same location as the bundled images (by default, "C:\Program Files \MediaMonkey\Plugins\DeviceImages\" or "C:\Program Files (x86)\MediaMonkey\Plugins\DeviceImages\")
3) Open MM4 and plug in your device. Wait for it to appear in Media Tree
4) Click on device's node in Media Tree
5) Click on "Options" tab.
6) In "Device image" field, click on the folder icon
7) Navigate to the folder where you saved the image and select it
8 ) Back to the device config page, click on "Apply" button and you're done!
If you are surfing and happen to come across any you could add the Motorola Dash and/or Amazon Kindle. No rush or anything but just a suggestion, since I have them in my arsenal. 
