I have plenty of ideas myself, but to give the participants even more choice I'll use as many of your suggestions as possible. I can't promise that I will use all of them though (it's not a request post), so feel free to suggest as many themes as you want. You can also always make multiple comments if you get more ideas later.
Feel free to repeat suggestions that someone else has already made. It DOES make it more likely that I will pick that theme! :)
If you participate regularly, I will use your suggestions more often.
If a theme has already been used (see the tag list to check), I won't use it again anytime soon, especially if it went on for multiple challenges.
If it might be difficult to find info/pictures/screencaps for some themes, it would be helpful if you provided links, but it's not required.
In each challenge I use one of your themes and it's credited as your suggestion.
Note: Some suggestions won't be credited as such, because I have quite a few themes prepared before they're suggested. It only means that sometimes two suggested themes per challenge will be used (one credited and one not), so it's a win-win. :D
Comments are not screened automatically, but later I screen the comments (along with my replies to them) in which all suggestions have already been used in challenges. I also screen comments that don't contain any suggestions after I reply to them. It makes it easier for me to see which comments with suggestions are still relevant. If something has been wrongly screened, please let me know!