Richard, as mentioned in the thread above, semi-stand development can have a nice effect on film. Some films react with "edge effects" or the halo-like edge seen between shadow and light. Most films will show an increase in apparent sharpness, sometimes with more pronounced grain.
Increased dilution with decreased agitation will allow high values to build more slowly, while the shadow values seem to gain density at a more constant rate. This type of development can work well in contrasty light, or with flat light. While this may seem to be somewhat contradictory, it holds up in the real world. In flat light, a long, slow development can help with added contrast in shadows and better separation in the tonal scale. The variable here can be simply with agitation cycles.
I use Pyrocat-hd with a 1:1:150 dilution for most things now, as I'm not too concerned with longer development times (strictly an amateur). The variation I use between minimal agitation and semi-stand is simply the frequency between agitation cycles. Minimal agitation uses 3 minutes between cycles, semi-stand is usually at 1/3's of total development time. Initial agitation is critical for this technique. You must have an even wetting of the film and initial agitation, or streaking and uneven development will be the result. Check some of the threads on APUG for more information. My gallery has a few examples in the recent uploads. Best, tim