FPS for the internet
If your source footage is interlaced, deinterlace it.  If your progressive frame rate is a constant 23.976, 24, 25, 29.97, or 30 fps, then keep the frame rate as it is, unless you require a very low bitrate and want to halve the frame rate.  These are all widely supported frame rates, although other arbitrary frame rates below 30 fps will often work as well.  Many popular devices only claim to support up to 30 fps.  If your source footage has a higher frame rate or you have a variable frame rate, consider converting it to one of these constant frame rates for wider compatibility.  Don't bother if you are submitting to YouTube as they will accept a wide range of frame rates and will re-encode the video for you at various quality levels.

If you are shooting all new footage specifically for the Internet, which will not be combined with existing footage, and you have your choice of frame rate, 30 fps (progressive) is a good and popular choice.  If you will not have any fast motion and want that cinematic look, you may prefer 24 fps.