javascript:a=prompt('Font:','Verdana');e=' style="background:';b='';for(i=32;i<256;i++){b+='<td'+e+'#999;font:10px/15px Verdana;text-align:center;width:40px;"><div'+e+'#fff;font:14px/30px '+a+';"> &#'+i+'; </div>'+i+'</td>'+((i+1)/16==parseInt((i+1)/16)?'</tr><tr>':'')};d=open('','c','scrollbars=1,height=500,width=740').document.write('<html><head><title>ASCII table: 14px '+a+'</title></head><body'+e+'#ccc;margin:0px;"><table cellspacing="3"><tr>'+b+'</tr></table></body></html>')
javascript:t=document.getElementsByTagName(prompt('Tags:','td'));a=prompt('Style attribute:','fontSize'),v=prompt('Style value:','11px');for(i=0;i<t.length;i++)void(t[i].style[a]=v)
javascript:alert('charCap\n\nŠ Thomas Russell\n\nhttp://users.bigpond.net.au/tamago/\n\n(Text areas now limited to 1024 letters).');x=document.getElementsByTagName('textarea');for(i=0;i<x.length;i++){void(x[i].onkeypress=function(){v=event.srcElement;if(v.value.length>1024){v.value=v.value.substring(0,1024)};status='Chars used: '+v.value.length+'/1024'})}
javascript:a=prompt('Enter cookie to delete:','');if(!a)a='';b=document.cookie.split('; ');c=false;for(i=0;i<b.length;i++)c=(b[i].substr(0,a.length+1)==a+'=')?true:c;document.cookie=a+'=;expires='+new Date().toGMTString();alert(c?'Cookie found and deleted.':'Cookie not found.')
javascript:h=prompt('Enter (case sensitive) string to replace:','');a=new RegExp(h,'');b=prompt('Enter replacement:',h);e=0;function f(w){var i,c=w.frames;for(i=0;i<c.length;i++){f(c[i])}d=w.document.body;if(d.tagName=='BODY'){g=d.innerHTML;while(a.test(g)&&e<150){g=g.replace(a,b);e++}d.innerHTML=g}}f(top);alert(e?'Changes made: '+e:'String not found.')
javascript:q=prompt('Search <http://www.dictionary.com/> for:','');if(q){void(window.open('http://dictionary.reference.com/search?q='+q,'_blank','height=500,left=50,scrollbars=1;top=50,width=700'))}
javascript:document.write('<html><head><title>makeLink: '+window.location+'</title></head><body style="font-size:10px;line-height:20px;font-family:Verdana;text-align:center;">Link: <a href="'+window.location+'" title="Link to '+window.location+'">'+window.location+'</a><br /><br />(To save, right click on link and select \'Save Target As\')</body></html>')
javascript:open('','','height=360,left=100,top=80,width='+(screen.width-200)).document.write('<html><head><title>moreCode</title></head><body style="background:#ccc;"><textarea id="b" style="height:300px;width:100%;"></text'+'area><div style="margin:10px;text-align:center;"><button style="font-size:11px;line-height:15px;font-family:Verdana;" onclick="opener.eval(b.value);if(confirm(\'Close window?\'))window.close()">Run code</button></div></body></html>')
javascript:function f(w){var i;for(i=0;i<w.frames.length;i++)f(w.frames[i]);x=w.document.all;for(j=0;j<x.length;j++){y=x[j].style;y.background='transparent';y.color=(x[j].href)?'#00f':'#000';y.borderColor='#000';y.borderWidth='1px';w.document.body.style.background='#fff'}};f(top)
javascript:a=0;b=new RegExp(prompt('Current price:',''),'');c=prompt('Preferred price:','');d=document;e=d.links;for(i=0;i<e.length;i++){if(b.test(e[i].href))a++;e[i].href=e[i].href.replace(b,c)};e=d.getElementsByTagName('input');for(i=0;i<e.length;i++){if(b.test(e[i].value))a++;e[i].value=e[i].value.replace(b,c)};alert(a>0?'Total changes made: '+a:'Price not found. Page may be in frames/not vulnerable to this exploit.')
javascript:a=prompt('Enter value to display:','document.URL');alert('Value of \''+a+'\' is:\n\n'+eval(a))
javascript:open().document.write('<html><body style="font-size:11px;line-height:15px;font-family:Verdana;">Cookies available to <span style="color:#00f;">'+document.URL+'</span>:<ol><li>'+(!document.cookie?'None.':document.cookie.split('; ').join('</li><li style="margin-top:10px;">'))+'</ul></body></html>')
javascript:function f(w,s,g){var i,q='';for(i=0;i<w.frames.length;i++)q+=f(w.frames[i],s+'.frames['+i+']',g+'\t');return(g+'<b>'+s+'</b> ('+(w.name?'\''+w.name+'\'':'Not named')+'): <a href="'+w.location+'">'+w.location+'</a>\n'+q)};open().document.write('<html><head><title>'+location+'</title></head><body><pre>'+f(top,'top','')+'</pre></body></html>')
javascript:a=[];b='';x=0;function f(w){var i,e=w.frames;for(i=0;i<e.length;i++)f(e[i]);l=w.document.links;for(j=0;j<l.length;j++){l[j].onmouseover='';l[j].onmouseout='';d=l[j].href;if(a.join().indexOf(d)==-1){a[x]=d;x++}}};f(top);a.sort();for(i=0;i<a.length;i++)b+='<li><a href="'+a[i]+'">'+a[i]+'</a></li>';open().document.write('<html><body style="font-size:11px;line-height:18px;font-family:Verdana;">Sorted links: '+document.URL+'<ol>'+b+'</ol></body></html>')
javascript:a=[];x=0;function f(w){var i,e=w.frames;for(i=0;i<e.length;i++)f(e[i]);l=w.document.images;for(j=0;j<l.length;j++){d=l[j].src;if(a.join().indexOf(d)==-1){a[x]=d;x++}}};f(top);a.sort();c='';for(k=0;k<a.length;k++){c+='<div style="background:#eee;border:none outset 1px;margin:20px;padding:10px;"><img src="'+a[k]+'" /><br /><br />'+a[k]+'</div>'};open().document.write('<html><body style="font:11px/15px Verdana;text-align:center;">Images from '+top.location+c+'</body></html>')
javascript:window.open().document.write('<html><head><title>innerHTML: '+document.URL+'</title></head><body><textarea style="height:100%;width:100%;">'+document.documentElement.outerHTML.replace(/<\/TEXTAREA>/gi,'womble')+'</text'+'area></body></html>')
javascript:u=prompt('Enter a URL:',location);if(u){void(location='view-source:'+u)}
Bookmarklets
I wrote the bookmarklets below - I hope you find them useful!