Wash your dishes with it only Andy you idiot!  Probably to hot for anything plastic to start with except for posts .
Circuit boards , you can use circuit board cleaner spray , dont ffs put them in the dishwasher 
With ramps the flame method works well enough ...

ROTFPMSL.. 

Pete has a good point regarding contamination or just the thought of your dishes mixing with old pinball grime is enough! Be different if it was just an old second handy in the workshop area just for this purpose but might be a bit of over kill there! People do use them to clean boards as Steevsee said and I have even heard of people cleaning wiring looms but be careful of the fabric insulated ones from EM's, I wouldn't try one of them! Now I think about it if I actually had a garage to setup for this stuff an old dishwasher might not be a bad idea as some you can adjust the temp which would be the consideration for plastics etc. Anyway that ain't going to happen but good tossing ideas around just the same. :) If you ever did try plastics I would test it on some old ones first ;)

Cheers: Brettski... :)