I am in agreement with Sundance regarding TAXI and as Herb pointed out, I also use their listings and deadlines to sharpen up my songwriting. I think Taxi is more relevant today than it was several years ago for several reasons. One, it has expanded into film/tv area and generates more placements for members. Second, it is an endless producer of details for song ideas, song construction and motivation to write outside of my normal genre of music.
I have also been playing with the BIAB melodist feature after learning about it from another thread here on the forum. It seems to be a good starting point to jump-start new song ideas. I began two new song ideas using it over this past weekend. It's akin to someone approaching me and asking "Can you write me a song in *** genre about ***".