There's plenty, but I would not recommend any other than the drip method. That is the most efficient, and acclimates the fish to everything (salinity, temperature, etc.)
hey there is another way you can set the bag in the tank till it gets the bag water to the saame temp as the tank then you can every 15-20 mins. u can add a little water to the bag likea 1/2 cup to a cup at a time till the bag is almost full then empty most of it out and do it again this works pretty well and should take only 1-1 1/2 an hour ive used it before it works pretty well.
I float the baggie for about 20 minutes until the temp is the same. Then every 5 min or so for the next hour I usually put a shot glass to a half a cup of water in the baggie. It seems to work for me.