"Mobile Suit In Action!", or "MSIA", is a very neat series of action figures by Bandai, originally based on the robots from the Mobile Suit Gundam anime series. They are very well articulated, and can stand in almost any pose you'd want them to. They are nicely sculpted, with lots of details, and are very accurate to their animated counterparts. Most of them come with all sorts of neat weapons and accessories, and a set of interchangable hands in different poses, so the robot can hold all its weapons stably and convincingly, or just make a fist.
Unfortunately, many of the figures can only be found in Japan or at a high markup in import stores. Fortunately, Bandai has committed to releasing American versions of these toys in great volume over the past few years.
In the year 2000 Bandai released the series of MSIAs based on the Gundam Wing series in the United States - actually released in the States before Japan, because Wing was at the time becoming the first Gundam series to air on American television, though it had been released years ago in Japan. Bandai subsequently released MSiAs for Mobile Suit Gundam, Gundam 0080, and Gundam 0083 in America, in preperation for those series' U.S. TV runs. Those series of figures were about half composed of new-mold figures for the American market (many of which have still not been released in Japan), since Gundam toys sell exceptionally well over here. Recently, the U.S. has seen the release of all-new MSiA series for Char's Counterattack and G-Gundam, a movie and TV series that haven't even aired on American television yet.
In the U.S., they come on big blueish cards (reddish cards for the Universal Century series, i.e. not Wing or G-Gundam) that just have the series logo on them, instead of the nice boxes with windows on three sides that they're packaged in in Japan. Also, the U.S. versions don't have the tiny sculpted lines and details painted in, and some lack the extra hands. Still, they're lots of fun to play with, pose, of just place atop your monitor, and they're a lot cheaper than the imports.
A couple of other series of robots have been released as MSIA-like figures, although under other names derived from their series. Several classic giant robots, some the ones known in the U.S. as Shogun Warriors, have been released as the "Super Robot In Action!" set. Also, the Dunbine and Billbine from Aura Battler Dunbine has been released, and I am not sure of the series name on its package. The Xabungle, from the series of the same name, has been released as a "Walker Machine In Action!" figure, as has the Walker Galliar. Most recently, the Ingram from Mobile Police Patlabor has been released as a "Labor In Action!" toy.