The Xtal Set Society has updated their site (again, links fixed, again) and added numerous items to their helpful catalog, useful for low power AMers. Why do we care? A radio concept called reciprocity.
Reciprocity means that receiving things should also work as transmitting things. Reciprocity is especially pertinent at the low power levels of, well, low power broadcasting.
If you've read about loading AM transmitters with air coils but you need a coil form, if you’re more sophisticated and want to try fine tuning with an air variable capacitor or if you are interested in winding a toroid core you can find parts and info here.
The catalog also features a handy formula page for calculating calculations. Also featured is a handy Frequency Allocation Chart showing frequencies allocated to 50K Watt stations and crowded spaces on the dial - both best avoided for low power work.
Lots of low power goodness to enjoy, thanks to Midnight Science.