One of my favorite events in Madrid is the Tapeo Mahou festival. Madrid offers several tapas tasting events, most of which included following a desired route to visit several bars and restaurants to taste their speciality tapa and enjoy a Mahou beer.
However, this event tops the charts for convenience, because participating restaurants set up stands at the Palacio de Deportes and everything is all in one location. You buy tickets and receive a map which includes all the names of the participating restaurants, their stand number and their offered tapa(s). Pick your favorites and visit those stands.
I´ve had an amazing time sampling the speciality tapas in the past and I can´t wait to stop in this weekend. Useful information:
From 12-430 pm and then from 8-midnight.
You must buy tickets for all, and the prices are:
Mahou Clasica or Sin: 2 fichas, 1 euro
Terico of Mixta, Light or Negra: 4 fichas (2 euros)
Tapas: 3 fichas (1.5 euros)