Flexpad is a unique appointment/to-do manager for DOS. It was apparently written as a replacement for the appointment book app in the 95LX, but it adapts to any screen size and runs well on any other DOS box including the other LXs. (But, see below for more on the subject of LX-related features.)
Rather than a traditional appointment book structure, Flexpad manages PIM data in free-form files which can contain a mixture of text and "labels" which define appointments, to-do entries, and the like. The labels can occur in any order in the file, and Flexpad will sort them out when creating one of its many alternate views of the data. Category and section labels are available, allowing the user to organize the data file in any way desired.
The initial state of Flexpad resembles a text editor -- in fact, it could easily be used as such. Pressing a key allows entry of a label; information for the label (appointment time, to-do priority, etc.) is prompted for in a dialog box. Entry of dates and times is very flexible, and allows arithmetic and all the usual shortcuts. The dialog allows entry of everything but the description of the appointment or to-do; that is taken from the next paragraph of text. (The whole paragraph... and multiple labels can apply to the same block of text.)
A text view of an appointment database isn't too useful all by itself, though, so Flexpad has a number of other viewing options. Most of them are rather obvious: daily, weekly, and monthly calendars, and list views of the same. A "month graph" shows the timelines for a whole month at a time, and a "preview" shows the next few days' appointments and todos. Another view sorts entries by section or category.
Flexpad works nicely on the 200LX and desktop PCs, adjusting its views to the 80x25 (or 64x16) screen. It has a couple of features that are 95LX-specific, though. Alarms are exported from Flexpad in ABK format, from which they can be imported into the 95LX appointment book so the LX will beep on schedule. (This file can be loaded into the 100/200 appointment app, at a slight cost in time for conversion; this seems like it would get somewhat cumbersome for people with large alarm lists.)
The other feature of Flexpad on the 95LX is its loader. On the 95LX, Flexpad loads as a TSR and includes a System Manager stub which can be installed as an application. This allows Flexpad to pop up over the other apps on demand, making it almost as good as a SysMgr app itself. On the 100 and 200, Flexpad must be run like any other DOS program, and is thus precludes running any other DOS app at the same time. Of course, the attraction of Flexpad for 100 and 200 owners is not likely to be as significant as for 95LX owners, because of the improved built-in appointment app in the newer machines.
Still, Flexpad is a unique and capable appointment and to-do manager, flexible yet small enough to fit in the palmtop. Its "style" is different from the built-in apps, so if you are looking for an alternative to what HP provided, Flexpad might be worth a look.