Funnelweb was written in the mid 1980's (circa 1984) by Tony (father) and Will (son) Mcgovern. It started out as "Funnelwriter" and was released as Vn 3.2. I was lucky enough to have received a copy directly from Oz just after release and Charles Good and I became the de facto distribution points of contact here in the US. It was develped as a response to Imagic Australia's rapacious pricing policy for the TI-Writer and E/A cartridges. It took the place of both. The kernel (i.e., UTIL1 or FW) went through many upgrades in the early years with the final release being Vn 4.40.
The editors have also been through many more upgrades. Vn 4.40 was the last strictly 40-column version. The current version is 5.21, which was released at the last Lima TI Faire, and takes advantage of the added 192K VRAM of a 9938/9958 system. The editors can be configured into a single 128k buffer, two 64K buffers, or four 32K buffers. You can, for example, have four 32K buffers in memory at once and cut and paste between them. The text editor gives the user a full 80 columns as does the A/L editor. There are numerous keys to select a host of functions. The full features are too numerous to discuss in a short article. There are some limited foreign language options (German for one).
The loaders in the kernel will load any program that can be loaded on the TI and, in addition to the two menus presented there, the 40-column version provides three additional menus and the 80-column version provides 6 more. The source code for the entire package is availble from several sources.
As a side note, Tony and I corresponded for many years and I was even fortunate to have spent some time with him at the notorious "Funnelweb Farms" in New South Wales - and yes there really are Funnelweb Spiders there. Unfortunately both Tony and Will have left the TI community - Tony due to health reasons and Will for The Silicon Valley.
Unfortunately, The 80-column version will not work on the F18A or Classic99 due to insufficient available VRAM.
As Owen said, paired with a RAMdisk (and the 80-column menu program, it is truly a formidible system!!