Similarly to my post on adding a link next to the Site Actions menu in the Left Ribbon, you can add a link on the right ribbon on SharePoint 2010 pages, next to the Welcome menu.
ExecuteOrDelayUntilScriptLoaded(ExecuteDefaultLoad, "sp.js"); var _rightRibbonContainer = null; function ExecuteDefaultLoad() { var isWikiEdit = false; if ( document.forms[MSOWebPartPageFormName]._wikiPageMode != null ) { if( document.forms[MSOWebPartPageFormName]._wikiPageMode.value == "Edit" ) { isWikiEdit = true; } } var inDesignMode = document.forms[MSOWebPartPageFormName].MSOLayout_InDesignMode.value; if (inDesignMode == "1" || isWikiEdit) { // page is in edit mode } else { LoadRightRibbon(); } } function LoadRightRibbon() { var ribbonContainerRowRight = document.getElementById("RibbonContainer-TabRowRight"); if( ribbonContainerRowRight != null ) { if( ribbonContainerRowRight.children != null && ribbonContainerRowRight.children[2] != null ) { if( ribbonContainerRowRight.children[2].children != null ) { _rightRibbonContainer = document.getElementById("RibbonContainer-TabRowRight").children[2].children[0]; if( _rightRibbonContainer != null ) { AddHelloLink(); } } } } } function AddHelloLink() { if( _rightRibbonContainer != null ) { var newSpan = document.createElement("span"); newSpan.innerHTML = '<a class="ms-menu-a" style="cursor:pointer;white-space:nowrap;" href="javascript:;" title="Hello!" onclick="window.location=\'/sites/test123\';return false;"><span><font color=\'#8ce352\'><b><i>Hello World!</i></b></font></span></a>'; newSpan.className = 'ms-SPLink ms-SpLinkButtonInActive ms-welcomeMenu'; newSpan.onmouseover= function() { this.className = "ms-SPLink ms-SpLinkButtonActive ms-welcomeMenu"}; newSpan.onmouseout= function() { this.className = "ms-SPLink ms-SpLinkButtonInActive ms-welcomeMenu"}; _rightRibbonContainer.insertBefore(newSpan, _rightRibbonContainer.children[0]); } }