For some time I have been getting good use from Harry's Filters in Irfanview. The burn tool can be very strong, so it is worth looking into the Darken feature, using BW Limiter Pro. It enhances textures in bark and stone.
The dramatic toning in this Sunflower was made with the Canon software that came with my Digital Rebel. Learning to use levels and to gently tweak the colour lines in a photo can help pastiche makers a lot.
