mimosinnet, try and disable javascript to get that page to load. For whatever reason, disabling javascript seems to be the only way to get some pages not to cause the browser(s) to crash. However, that still doesn't explain as to why some sites that use Flash, Java or Javascript load fine for me and others cause this problem.
I'm not sure if this was what you're looking for, but according to eix, this is what came up for me with respect to useflags for Firefox (I'm still running FF 2.0.0.17 as 3.0 was not available in portage it seemed when I was emerging):
(bindist debug gnome ipv6 java -filepicker -iceweasel -linguas_af -linguas_ar -linguas_be -linguas_bg -linguas_ca -linguas_cs -linguas_da -linguas_de -linguas_el -linguas_en -linguas_en_GB -linguas_en_US -linguas_es -linguas_es_AR -linguas_es_ES -linguas_eu -linguas_fi -linguas_fr -linguas_fy -linguas_fy_NL -linguas_ga -linguas_ga_IE -linguas_gu -linguas_gu_IN -linguas_he -linguas_hu -linguas_it -linguas_ja -linguas_ka -linguas_ko -linguas_ku -linguas_lt -linguas_mk -linguas_mn -linguas_nb -linguas_nb_NO -linguas_nl -linguas_nn -linguas_nn_NO -linguas_pa -linguas_pa_IN -linguas_pl -linguas_pt -linguas_pt_BR -linguas_pt_PT -linguas_ro -linguas_ru -linguas_sk -linguas_sl -linguas_sv -linguas_sv_SE -linguas_tr -linguas_uk -linguas_zh -linguas_zh_CN -linguas_zh_TW -mozdevelop -moznopango -restrict-javascript -xforms -xinerama -xprint)
The italicized portion appears in red in eix.
For Sea Monkey (1.1.12), I got this:
(crypt debug gnome ipv6 java postgres -ldap -mozdevelop -moznocompose -moznoirc -moznomail -moznopango -moznoroaming -xforms -xinerama -xprint)
Again, italicized text is actually in red.
Also, not that it really matters to me personally as it's the same browser (just a different name) and I remember it being this way before (I can't remember now just how long ago this was, but I remember the reason had something to do with licensing issues or trademark protection and, at some point, it went back to the original name), but is it just me that now has Firefox showing up as Bon Echo?