I also came across some interesting links for IFR pilots. The Searchable Preferred Routes Database is one that will save a time when hunting for routings in the AFD. This is one of a number of Online Products offered by the FAA ATC Command Center
Finally, the Aviation Weather Center has some interesting products. For IFR flight, the Icing Page product gives an interesting look at Ice [hint: mouse over the altitude column on the right side of the display] The original version of this article referenced the experimental "Current Icing Potential" page, which has been replaced by this new Icing page