Never? You are not alone. None of the maintenance solutions I use includes functionality to rebuild a heap, and that includes Maintanance Plans and Ola Hallengren's maintenance solution.
"So why would you want to rebuild a heap, when it isn't sorted in the first place?", you ask. The answer is to get rid of Forwarding Pointers, and these can really hurt performance by adding lots more logical and physical reads, and random I/O. See for instance this from Kalen Delaney, this from Hugo Kornelis and this from the SQLCAT team.
SQL Server 2008 added the ALTER TABLE command, with the REBUILD clause. And this is what I'm using in my procedure rebuild_heaps which rebuilds all fragmented heaps on a SQL Server.
You find the procedure here: http://www.karaszi.com/SQLServer/util_rebuild_heaps.asp.