There were certainly political implications for the Crusades in Europe before the 4th Crusade: in fact, for the most part they were hugely disruptive. A lot of my examples will come from the First Crusade, because it's the one I know best and because the political implications of the 2nd and 3rd Crusades are more immediately obvious, because of the involvement of major kings in them: Louis VI 'the Fat' of France in the 2nd, and Philip II Augustus of France, Richard I Lionheart of England and Frederick I Barbarossa of the German Empire. The expense of sending their monarchs on Crusade, plus the absence of the ruler for years at a time (in Barbarossa's case, forever, as he famously drowned while crossing a river in Anatolia), were major, with the most well known being the regency of John in England in the absence of his elder brother. I'm sure there are other contributors who can add more detail here.

The 1st Crusade is a little different, partly because it involved no kings or emperors and was, being the first, organised on a rather more ad hoc basis. Most of the political ramifications, however, arose from the same reason they did in later Crusades, namely the great expense and effort of embarking on such a long and dangerous journey. In fact, so many knights and nobles sold or mortgaged their lands, mostly to the church, in order to finance the venture, that the property market seems to have taken a big hit throughout France and the church ended up expanding its already extensive portfolio of lands across Europe: causing many small, local land disputes in the decades which followed.

The First Crusade also had political implications in that many of its leading figures did not return, or returned in significantly worsened positions. The best example is Duke Robert II 'Curthose' of Normandy. Robert mortgaged his duchy to his baby brother, Henry I of England, in order to pay for the Crusade. On his return however, he had great difficulty in getting it back off Henry, eventually being beaten in battle by his brother and imprisoned for life in 1106. For the next century, the titles of Duke of Normandy and King of England were always claimed by the same person, until Philip Augustus' conquest in 1204. Godfrey of Bouillon, Duke of Lower Lotharingia, who would eventually become Prince of Jerusalem, was another; despite his title and twenty years of service to Emperor Henry IV, in 1095 he found himself politically marginal and without much of a powerbase in his duchy. Liquidating his lands, his intention was always to stay in the Holy Land, which led to fierce local power struggles in Lower Lotharingia for the following decade before a new duke from a rival family emerged.

Lastly, there was the disruption caused by the Crusading armies as they marched through Europe on their way to the Holy Land. Most famously is the massacre of Jews in Worms, Speyer, Mainz and Cologne by an army led by Count Emich of Flonheim, but the peasant army of Peter the Hermit, which also passed through the Rhineland, was notorious for looting and foraging through the countryside in order to feed itself, leading to numerous stand-offs and violent confrontations with local communities, notably in Hungary. This is a symptom of the rather hap-hazard organisation of the First Crusade, with armies such as Peter's having little in the way of supply lines, finances or discipline.

Hopefully, this gives you a flavour of some of the political ramifications, although, to tell the truth you could fill a book with them. If you want more information, Christopher Tyerman's God's War is a good general intro to the Crusades, which has lots of follow up bibliography. And feel free to ask any follow-up questions, which I'll do my best to answer.