Slovakia seems to have a rather weak and fragmented party system, with a lot of parties in the 5-15% support range and changes in the competing parties being common.
Is there any sign of the development of the sort of relatively stable constellations of parties you get in western Europe?
On the other hand, what do you mean by weak party system? Do you mean volatile? IMO in other senses, namely the longevity of some formations and the longevity of the base/political cadre of other formations (e.g. liberals); the strong party member base of some parties (especially HZDS, SNS, Hungarian party); and the so far generally high voter turnout (1990: 95.39%, 1992: 84.20%, 1994: 75.65%, 1998: 84.24%, 2002: 70.06%, *: reelections), I'd call it a strong party system. (And under different circumstances, I'd see volatility as a positive sign, e.g. that parties can't be entrenched in power.)
Also, while I agree that the lack of two major parties can be characterised as more fragmented party landscape, the number of important parties is not high (compares to France or Germany or the Netherlands or Canada) -- unlike say in Poland or Italy. *Lunatic*, n. One whose delusions are out of fashion.
I may be looking at this from too narrow a British perspective. We have three major parties in the House of Commons. Two of them have roots which go back to the seventeenth century and the third has existed for more than a century.
It is rare for British parties or political traditions to reorganise themselves or suffer major disruption, in the way that seems to happen often in many Central European countries.
The British Conservative Party has existed, more or less as it is today, since the early nineteenth century when the late William Pitt the Younger's former supporters came to call themselves by the historic name of the Tory Party (although not all of them belonged to the Tory tradition as it had existed in the eighteenth century). It adopted its current name in the 1830s and split over free trade and protection in the 1840s. The protectionist wing became the official party. It allied with the Liberal Unionist (opponents of devolution to Ireland) after 1886 and absorbed them in 1912.
The members of the Whig tradition in British politics, who had not supported Pitt's last Ministry, and other anti-Conservative groups became more cohesive in the first half of the nineteenth century. Whigs, Liberals, Radicals, Reformers, Liberal Conservatives (the Conservatives who broke away from that party in support of free trade) and Irish Oppositionists gradually assembled themselves into a Liberal Party (by at the latest 1859). The historic Liberal Party was in alliance with a Social Democratic Party, which broke away from the Labour Party in 1981. The two groups merged to form what are now the Liberal Democrats in 1988.
The Labour Representation Committee was formed in 1900 and became the Labour Party in 1906.
The reasons for the high degree of stability over time and the small number of major Parliamentary parties is the first past the post electoral system and a political culture that puts a very high value on party loyalty and regularity.
I observe that other European democracies tend to have more major parties. This is not purely due to electoral mechanics. Systems like the French and Italian tend to produce numerous parties and push them into two blocs. Systems like those in Germany (since unification), the Low Countries and Scandinavia tend to have five or so significant parties but their identities and approximate level of support tend to remain fairly stable over prolonged periods.
It may be that party systems in Central Europe will settle down as people and politicians develop loyalty to particular political brands over a period. From what I have read it did take twenty years or so for the West German parties to develop stable allegiance from their electors, at the start of the Federal Republic.
Of course I am theorising from a distance. People who live in a country may have a quite different view of how the politics of their nation and its neighbours are developing.
