To be honest, keyboard and mouse are so subjective that no one can choose them for you. What's great for one person might be unusable for the next. The best piece of advice I can offer is don't skimp on them. Combined with the monitor, they're the only bits of your computer that you actually touch or see (unless you spend hours looking at your case and stroking it lovingly I guess), so spend as much as you can and it will make a big difference in your day to day experience, more so than an extra 200Mhz on your CPU speed or extra 3 fps.
My recent choice was a Logitech G9, MS Sidewinder X6 and Razer Destructor mat (I use a headset so can't comment on speakers) and I'm really happy with them all. Other forum favourites are:
Mice: MX518, Razer Deathadder (as above)
Keyboards: Logitech G15, Saitek Eclipse series
As for mats that depends whether you like cloth or prefer a hard surface. Also, what kind of gaming do you do? FPS requirements are generally different from MMORPGs or RTS gaming needs.
Sorry to be a bit vague, but hope that helps in a twisted kind of way