(FORTUNE Magazine) – Need a reality check? Try watching one of your stocks fall 40% in 36 hours. That's exactly what happened to shareholders of stun-gun maker Taser (TASR, $68)* on April 20, after the company announced strong if not quite stunning earnings results. No one could blame investors for taking their profits, of course--not after the stock's epic run from below $3 to $128 in just a year transformed it from unknown quantity to It Stock.

Undaunted by the cautionary aspects of the mini-mania, speculative investors are plowing money into the stocks of other pipsqueak companies that specialize in security--like pepper-spray specialist Mace Security International (MACE, $4), which actually gets most of its sales from car-and truck-wash services. On April 13, shares of Mace hit $14.80--a 385% two-day run--after it introduced a new surveillance camera, only to drop back off. IPIX (IPIX, $8), a former web photo host turned surveillance-camera maker, was up 38% over the same two days and rose roughly 1,000% in three weeks. "Some investors are in a frenzy in search of the next Taser," says analyst Steven Gish of Roth Capital Partners in Newport Beach, Calif.

Other factors are at work. Analysts say the 9/11 hearings and the train bombings in Madrid have renewed fears of terrorist attacks and thus drawn attention to companies that might benefit from beefed-up security. And the 21% premium shareholders received in GE's recent $900 million cash bid for airport-security specialist InVision Technologies (INVN, $49), Gish says, "has probably spurred, erroneously, another round of takeover speculation."

One longshot to watch is Drexler Technology (DRXR, $16), which makes high-tech ID cards used by U.S. immigration services and foreign governments. Drexler has acquired two German companies and will try to grab the British ID-card business if Parliament passes mandatory-ID legislation this summer. But even Gish, who likes the stock, labels it "highly speculative." We wouldn't be shocked by a Taser-like run--up or down.

--Kate Bonamici