This is a cool little trick to know – very useful especially if you use a load of the same webpages everyday. To set multiple homepages in firefox what you need to do is go to tools then options then use the | symbol in between the webpages, so for example;
https://www.techontour.com | http://www.bbc.co.uk | http://web.techontour.com
I currently use 6 homepages and I have not reached any limitation. It is actually quite a time saver – given I check the same sites everyday!!