Big Bob's Beepers is Big Bob Pataki's pager emporium. The business seems to be majorly his creation (due to his name being the store's name) and is his main source of income. The fact that the Pataki household, throughout the series, seems fairly large and well-established, points out that it is reasonably productive, due to the beeper's then relatively high price. Big Bob is the sole manager and head of the business, the only two people who seemingly have any sway within the store's management being his associate Nick, and on one occasion, Miriam.
The store seems to be the one thing that Big Bob is passionate about, as he is constantly attempting to expand it, at the cost of areas that are important to the kids, ("Save The Tree") or even the living places of the people who live around him ("Hey Arnold!: The Movie"). He also seizes every possible opportunity to promote it ("Runaway Float") and add more people to its clientele. As such, the store and its owner's concern with gaining even more money tends to be the catalyst for many episodes (and memorably, the movie).
However, it seems that Big Bob's aggressive approach to managing is holding the store back: when Miriam briefly takes over during "The Beeper Queen", Big Bob's Beepers takes a leap, with her closing important deals, forming valuable business alliances and coming up with creative ways to promoting the store that aren't in sync with Bob's expansionist, mercenary approach.
A massive mall store called Big Bob's Super Beeper Emporium was to be this store's next generation incarnation, once Future Tech Industries demolished Arnold's neighborhood and built a futuristic mall. However, when Big Bob found out that Mr. Scheck didn't respect the bargain, this store will most probably not exist.